Wow, that was just awful. Before this episode, I gave Peter a pass because he was dorky but boyishly cute. He loves his mom. He's awkward around women. He likes roller coasters.
Tonight, nope, nope, nope.
Peter, if you are actually serious about someone (and it's clear how much he likes Madison), and you know how she feels about the Fantasy Suite, you shouldn't sleep with other people. It's not like feeling bad about not inviting your neighbors to your party or offering a piece of the office birthday cake to people nearby. It's not rude to not sleep with someone when you have strong feelings for someone else.
Good for Madison for staying true to herself.