Aw, the fun part of writing! Guess this depends on any fears, phobias, they may have. For more fun, don’t actually have him “inside”, but close enough where the assumption is made, especially if there’s any other malicious actors nearby who might’ve staged it (ie, took the opportunity after the two passed out to move him onto her, placed a condom with a dab of mayo in the tip nearby, etc). Is the guy panicked now that he’s possibly a rapist? Is she offended? Or, is the mutual attitude “it’s about time?” (It can be mixed too, one thinks “not a big deal”, while the other is very upset/calling-police?) This is definitely a mixed bag, and gotta know the characters better before a good response can be had IMO.