I also, in no way, mean for this to devolve into a Spuffy vs Bangel argument; that's a completely separate argument (I ship them BOTH, FYI, with an overwhelming love of the OT3: Spuffangel FTW!) and it's an argument I'm well & truly over. Also, comparing Spuffy to Bangel in relation to this scene does no one any favours, as far as I've seen.
My main reason for sharing this is because, while I see many members of the fandom have a wide variety of different opinions in regards to this scene, very few have come close to how I view it. And how I've always viewed it, right from the very first airing.
I don't believe, nor have I ever, that Spike was attempting to rape Buffy, in the (now very much so) infamous "bathroom scene" from the Buffy the Vampire Slayer episode "Seeing Red" (#6.19). I believe Spike was simply following the "pattern" of every previous sexual encounter he & Buffy had ever had. The main difference being that when Buffy said "No" this time, she actually meant it.
Let's look at some of those previous sexual encounters for comparison:
Starting from their very first sexual encounter in the Season 6 episode "Smashed," (#6.9) Buffy & Spike's sex life has followed a very recognisable pattern. First violence (they beat the crap out of each other)/verbal abuse (they verbally beat the crap out of each other); Buffy declares her hatred/disgust for Spike and/or actually uses the words "Stop" & "No"; & then they, enthusiastically & consensually, bone (usually also very violently).
Even the morning after, in the next episode "Wrecked," (#6.10) follows that same pattern. Buffy declares her hatred/disgust for Spike, tells him it's never gonna happen again; actually uses the words "Stop" & "No" & then proceeds to initiate one hell of a sexy make-out session; which then ends with Buffy declaring further disgust & a threat to kill Spike should he tell anyone about the aforementioned sexy times (see the end of the above clip, or the transcript below).
Buffy pushes his hand away, struggles against him.
SPIKE: (grinning) Make me.
BUFFY: No! No!
She continues struggling for about another half second and then grabs his face and kisses him. She puts her arms around his neck and moans. They kiss for a moment.
Cut to later that same episode & Buffy comes running to Spike for help in finding Dawn; while looking for Rack's cloaked hideout they bicker, with Buffy eventually declaring she wants Spike completely out of her life; & then, when they do find Dawn, she turns to Spike to help her get Dawn to the hospital, leaving him to take care of Dawn on his own while she confronts Willow.
This pattern of conflicting "get out of my life"/"wait, take care of my sister" back & forth is another continuing theme of their relationship, that can be nothing but confusing & frustrating for Spike. (I raise this point, not to excuse any kind of behaviour, but because it's a direct comparison to their sexual encounters; that constant "No, I don't want it"/"Violently enthusiastic sex" that occurs throughout their relationship during this season)
The following episode "Gone" (#6.11) begins with the very same type of encounter: Buffy tries to initiate violence, Spike gets to groping, Buffy (again) says the words "Stop that" while sighing in pleasure & this time, just for something different, they're interrupted by Xander (see clip below).
It's, interestingly, later in this episode where their roles are virtually reversed. After having invisible sexy times, Spike is the one who tells Buffy to "Push off" after realising she was only there because he couldn't "see her," she then proceeds to ignore his protests & initiates some more sexy times (see below):
In the next episode "Doublemeat Palace" (#6.12) we see Spike visit Buffy's new place of work where she, again, tells him to "Go away" & then proceeds to screw him against the alleyway wall.
"Dead Things" (#6.13) begins in Spike's crypt where we see the aftermath of Buffy & Spike's most recent sexy times (the violent beginnings are only heavily implied here, we don't see it; although we hear the end of their violent sexual encounter). We also get to see Spike & Buffy "have a conversation" that actually results in them both pointing out how violence plays such a huge part in their sex life:
SPIKE: Well, isn't this usually the part where you ... kick me in the head and run out, virtue fluttering?
BUFFY: That's the plan ... (embarrassed) ...soon as my legs start working.
Again, later in this episode, we see yet another sexual encounter follow the usual script. Buffy says "Don't," Spike tells her "Stop me," & then they bone, while Spike whispers not-so-sweet nothings in Buffy's ear about how she "belongs in the dark" with him:
This episode also shows us, arguably, the least violent sexual encounter between Spike & Buffy, but which proves only to be a nightmare of Buffy's. The most violent aspects of her nightmare tend to be directed at Katrina (the girl she accidentally kills in the episode), not Spike.
In "Older and Far Away" (#6.14), whilst there isn't any actual sex in this episode, we do see the pattern continue:
Spike walks up to her, smirking. He tries to take her hands but she pulls them away. But she is smiling too.
BUFFY: Stop it. Someone's gonna see.
She walks toward the kitchen. Spike follows, stops her at the doorway, putting one hand on the wall beside her head to block her way.
He puts his other hand on her shoulder, runs it down her arm, takes her hand and pulls it onto his thigh.
"As You Were" (#6.15), again, sees the episode begin with a very familiar pattern. This time Buffy says "No" before Spike can even make the suggestion of sexy times; & continually says variations of "No" throughout the conversation, until they (you guessed it) bone!
BUFFY: No, Spike.
SPIKE: No? What kind of answer is that, you haven't even heard the question yet.
BUFFY: I don't have to. We both know what you're thinking.
SPIKE: (grins) And we both know ... that I'm not the only one thinking it.
He puts his hand out as if to grab her coat collar, and leans in as if to kiss her.
Buffy slaps his hand away.
BUFFY: No! Not here.
SPIKE: Why not? (pouting)
BUFFY: Dawn. (looks toward the house) She's inside waiting for dinner, she's counting on me. I'm not letting her down by letting you in.
SPIKE: So it's the fear of getting caught, then, is it?
BUFFY: Reason number one on a very long list. (turns to go)
SPIKE: Needn't be an obstacle.
He takes her hand and pulls her toward the tree. Longer shot of the two of them moving along the side of the building.
BUFFY: (sighs) Spike, I mean it. Come on.
SPIKE: I hear you're serious. So am I. I want you ... you want me...
Cut to a closer shot as Buffy has her back up against the tree and Spike is right in her face.
SPIKE: ...I can't go inside, so ... maybe the time is right ... for you to come outside.
Buffy sighs, looks at the house, then back at Spike. He slowly leans in to kiss her.
Cut to a long shot again. They kiss, Buffy drops the paper bag on the ground, and Spike pulls her around so that the tree obscures them from our view.
Another interesting sidenote, the sex scene we see later in this episode (The "Tell me you love me" scene) is the first & only time we see any sexual encounter between Spike & Buffy that doesn't contain some variation of Buffy (or Spike) saying "No." Seven episodes (or several months in show time) & this is the first & only time that happens!
The end of this episode is where we see Buffy call off her relationship with Spike, and to seemingly actually mean it this time. And we see Spike realising that she actually means it this time.
"Entropy" (#6.18) has no sex between Buffy & Spike, but it does have an exchange between them where Buffy admits she knows Spike would never willingly hurt her. Which speaks volumes, really:
SPIKE: (quietly) I don't hurt you.
He walks a few steps away.
BUFFY: I know.
SPIKE: No, you don't. I've tried to make it clear to you, but you won't see it. (pauses) Something happened to me. The way I feel ... about you ... it's different. And no matter how hard you try to convince yourself it isn't, it's real.
BUFFY: I think it is.
Beat. He looks at her.
BUFFY: For you.
Now we get to the actual episode "Seeing Red" (#6.19) itself.
After Dawn confronts Spike about his dalliance with Anya, asking him how he could do that if he really loved Buffy, Spike's prompted to go & apologise to Buffy. Which, after asking after her well-being (she's obviously hurt), he does:
SPIKE: (softly) I'm sorry. Not that it matters any more, but I needed you to know that.
SPIKE: Because I care about you.
BUFFY: Then you might want to try the not sleeping with my friends.
SPIKE: I didn't go to Anya for that. I was looking for a spell.
BUFFY: (outraged) You were going to use a spell on me?
SPIKE: (sighs, exasperated) It wasn't for you! I wanted something . (puts hand on his chest) Anything to make these feelings stop. (angrier) I just wanted it to stop!
That's his motivation for going to see her. His only motivation. Further into the conversation & we get Buffy admitting, for the first time, that she does have feelings for Spike:
BUFFY: (calmer) I have feelings for you. I do. But it's not love. I could never trust you enough for it to be love.
SPIKE: (laughing) Trust is for old marrieds, Buffy. (Buffy rolling her eyes) Great love is wild ... and passionate and dangerous. It burns and consumes.
BUFFY: Until there's nothing left. Love like that doesn't last.
SPIKE: (pacing) I know you feel like I do. You don't have to hide it anymore.
BUFFY: (rolling her eyes) Spike, please stop this.
SPIKE: (whispers) Let yourself feel it.
This is obviously what prompts Spike into believing a return to their usual history of sexual encounters is the way to go. Buffy's just admitted that she cares about him, & given their previous sexual encounters have been predicated on Buffy declaring the exact opposite, getting back to sex seems the obvious answer to Spike. Also, given that all of their previous sexual encounters have begun with Buffy saying "No," sometimes repeatedly, this, to Spike, seems to be following the usual script. Even the violence with which this encounter takes place is completely following their previous pattern.
We, as an audience, are aware that the previous times Buffy has said "No" she didn't actually mean it; just as we, as an audience, having seen what Buffy has gone through earlier in this episode (& in the preceding episodes, such as her complete mind-fuck in "Normal Again"), understand that this time when Buffy says "No" she does actually mean it. But Spike has no way of knowing that. All Spike has to go off of is their previous violent, verbally abusive & consensual sexual encounters, which all started the exact same way this scene does. Buffy says "No" & then they bone.
Spike's above expression is often interpreted as Spike's horror at realising what he's done, and I don't disagree with that, but I think it's not just that. This expression is Spike realising that Buffy actually means "No" this time, and then realising, with horror, how his actions will be construed by Buffy as a result of her actually meaning it. He had no way of knowing prior to Buffy physically kicking him off of her & looking so upset, that his actions were anything other than their usual means of initiating sex.
Further to that, when Spike realises that Buffy actually meant "No" this time, he backs off; he stays backed off. And then afterwards, he leaves to regain his soul; which I think gets glossed over quite a bit. The fact that a soulless evil being chooses to go through torturous trials in order to regain his soul is actually a huge deal! He's (to our knowledge) the only one to ever do that. There can really be no greater sign of remorse than that, & yet he goes so many steps further in order to never be that kind of monster towards Buffy ever again. Because he's never been that kind of monster before. In all of the tales of Spike's previous history, rape or sexual assault were never a part of it. He's killed, maimed & tortured, sure, but never rape.
[You'll notice I've not brought up the "Spike doesn't have a soul" argument, & that's because I believe that even soulless Spike would call "bullshit" on that. I don't think any version of Spike, soulless or not, would ever intentionally attempt to rape, or sexually assault, anyone. I believe violence has likely always played a huge part in his sexual encounters, but never rape (at least not with him being the rapist). I think Spike's soulless nature is what lends itself to the violent nature of his sex-life, but even soulless, he would draw the line.]
So, in conclusion, no, I don't view Spike's actions in that scene as attempted rape. With all the evidence available to him, he was simply initiating a regular (for them) sexual encounter with someone who had repeatedly told him no & then had sex with him.
P.S. I've ummed & aahed over sharing my opinions on this for years, but for whatever reason, I've finally attempted to put it in to words. This is my first time ever writing anything like this, & I tried to be as concise & clear as possible, but I may have gotten rambley at certain points, so I hope it all makes sense. Also, if you see any typos, let me know!
Credit to BuffyWorld for the transcript excerpts