The whole thing with Hannah doesn't make sense. This was filmed during DWTS, and she was getting tons of national exposure and attention. Why go back to Peter? She could have easily had her cryfest on DWTS with Alan and have it work in her favor for voting.
So, bear with me here. (Yes, thinking about this is my way of relaxing after work.)
I've always thought the 4 times thing was handled strangely ostentatiously, from Hannah's brazen declaration at AFTR (or was it MTA) to his parents' cheering. And even after the bizarre sex storytelling, Peter made the slightly odd comment of "that's how I remember it, too." It's almost like she's his wingwoman, giving him street cred.
I don't believe she wants him at all. Like a lot of women her age, she likes unattainable personality-challenged man-boys. Peter is perfectly easy on the eyes but way too normal.
I wonder if this was simply all a ploy to bump up Peter's desirability and, of course, ratings.