It's interesting that you characterize this story as Rodney not being good at relationships, when it seems to me that he's pretty good at keeping the relationship that's most important to him. The thrust of the story (or at least the last scene) seems to be not that Rodney's relationship with Jennifer didn't work at all, but that his relationship with his best friend was just more important. /imho.

In fact, I'm not entirely sure this story shouldn't be characterized as John&Rodney rather than "Keller/McKay", when lines like "They're not sleeping together. He just… cares about him more than me." make an apprearance :)