I agree with you guys on the friendship thing. Ryan and Marissa both admitted that they were never really friends before they got together. This is from "The Way We Were:"

Ryan: ...Look, I’m sorry. For right now we should....we should just be friends.
Marissa: Friends? (Ryan looks at her) Ryan we're not friends, we were never just friends.
Ryan: I guess that was the problem then.

And that was the problem, they kind of jumped straight into a relationship without really being friends, so when it was over, it was just over. They couldn't hang out and try to work things out. But I really feel like they've developed a friendship this season, a good base for a new chance at a relationship. That's what I'm hoping, anyway!