I don't think anything happened between Buffy and Xander at the party. That would be really weird if they had decided to cheat just like that and had sex in the room while Dawn and Willow were in the kitchen, who could've heard them since the party hasn't started, and both Buffy and Xander would've been sober at the time so even the alcohol would've been no excuse, and then Buffy went and hit on first Spike, then Riley ('cause, what, Xander didn't get the job done?
) and ended up naked in her bed with someone's belt in it, while Xander was smooching Dawn? And Buffy later felt ashamed for hitting on a married man, but not for having sex with her sister's serious boyfriend?! Makes no sense at all.
Even those who think Xander may be the father think that something happened before the party and that this was what they were discussing, but I don't believe it, it would be really OOC and total character assassination for both; secondly, it seemed like he
was the one with the problem (whatever it was, we still haven't learned) and she was telling him to confide in her ("Do you want to talk about it?" and holding his hand) which really doesn't seem like something she would do if she had slept with him. I can't imagine how or why she'd do that to Dawn, especially since she's not in love with Xander, she described them as "my sister, and my sister's boyfriend who's also my best friend" in this issue. But if somehow she did, she would feel incredibly guilty over it. I just don't see how that would work at all.
Besides, Jeanty and Allie have been hinting from the start that something happened at the party that changes Buffy's life. Buffy getting drunk seems to have been a setup to get her pregnant by some anonymous or near anonymous guy. Which opens all sorts of unpleasant questions, since we don't even know if she managed to remember what happened. In #1 she suspected she might have had sex but couldn't remember or guess who with. Unless she remembers, we have a dubious consent situation and probably a lot of trauma for Buffy.
I hate that they're leaving the audience with the stupid "who's the daddy" controversy. The identity of the father probably isn't even important at all. They just wanted to have an unplanned pregnancy storyline for Buffy and this is the way they decided to bring it about. I'll be OK with it as long as it's none of the characters we know and care about. Riley is too decent and happily married to have sex with drunken Buffy, and since he was sober it would make him look really bad, at the best he'd be a real sleezebag. Most people think that the most likely candidate is Heinrich the neighbor, who was probably introduced (even though we haven't seen him) just for that purpose. What doesn't quite sit well with me there is that it would mean that Buffy went to see this guy she didn't even know, visited him and introduced herself and immediately had sex with him within the 20 minutes she was there and then came back home to the party, which is really weird and OOC even with the alcohol involved.
It's also possible that it's some anonymous guy from the party we'll never see, or even (less likely) Tumble or Buffy's boss or some other human male at the party.
I'll really hate this if they treat it in a nudge nudge wink wink way as they have so far. Heroine gets pregnant from a blackout drunk sex she doesn't even remember and which therefore she might have been too drunk to consent to? Ugh. I hope they realize the problematic aspects of this. And then we get a month's worth of "who's the daddy" fandom wanks? Please clarify what happened in the next issue and kill this discussion, please.