This would be so much sweeter if she hadn't been drunk out of her mind that night :/ The ML is so emotionally vulnerable too, they had such a bonding moment - it's sad she doesn't remember any of it. There on that bed she clearly 1) knows who he is and 2) is pretty enthustiatic about the kissing, meaning she is in fact interested in going to bed with him so that'd be pointing towards her consenting but she's also like... superdrunk. She might not have gone to bed with him like this, after a party without being engaged, if she wasn't literally blizzed - i.e. not capable of giving consent -> this is sexual assault.
The main saving grace for the ML is that he expects her to remember everything so he might not have realized that she was blackout drunk. I mean, a drunk person could still consent, just... not one as drunk as the FL was. Still kinda sketchy, but yknow... I honestly wish she'd just come clean about her not remembering anything. I doubt she will, or if she does, I doubt the ML will realize that he fucked up that night.