"Yeah," Peter says simply, because he's not sure how else to respond to it. On some level, it makes him uncomfortable, but he's not sure if it's because she thought she'd lose her virginity to Max or that virginity really didn't seem like that big of a deal to him or that he never felt that way about someone else or that it was becoming increasingly difficult for him to entirely believe that Liz was over him when she was telling him stuff like this.