Yeah, this might be a bit mean of me, but Josh is a total coward. Notice how it was Valencia who had to end that relationship, not him, even though he was clearly unhappy in it. Also, in the first episode, he breaks up with Rebecca on the last day of summer camp, right before he runs off to be picked up by his parents. He chose to break up with her right at the moment when he wouldn't have to deal with any fallout. So yeah, I wouldn't be at all surprised if Rebecca and Josh are still together when season 2 starts. In addition to that his family totally loves her, and he kind of screwed over his best friend in order to be with her, both of which could lead to a feeling of obligation to be in the relationship. I recently re-watched the pilot and Josh says something like "you probably don't remember me much do you?" At first, it seemed to me to be boilerplate meeting-someone-you-haven't-seen-in-a-long-time language, but now I wonder if Josh actually remembers his time at camp that well.
OMG, this comparison really kind of fits. Scarlett O'Hara is actually supposed to be 16 at the beginning of Gone With the Wind. So, Rebecca is Scarlett. Josh is Ashley, aka her teenaged fantasy crush that she holds onto. Greg is Rhett, the cynical guy who sees through her, but can't help but adore her in spite of himself. It makes sense to me.
I really couldn't enjoy the reunion between Rebecca and Paula. I know this is Sitcomland, and the standards of behavior are different, but Paula is a bit of a sociopath. That song rocked though!