The bedroom scene that Peter didn't remember was actually Peter, after a drunken one night stand. She was mad because he didn't remember that. They're not saying that he didn't sleep with her there (although if I understand K-Box correctly, they don't come right out and say it either, they use the same sort of ambiguous language that could be interpretted either way).
The 'making out in the kitchen' happened after that, but not with Peter, with the Chameleon.