I don't know if "friends with benefits" is the term I'd use for them. I think they're two people who tried their hand at a relationship and it didn't go the way they'd planned, so they decided to back off. But the problem is, the feelings didn't go away. They still care about each other, they still want each other, they still have that spark. So they may tell themselves they can be friends, but then they see each other, and...
"Friends with benefits," to me, is more casual, it doesn't have the same depth of feeling involved. And it's usually not something you try to resist. If you're friends with benefits, then you're friends with benefits, you both know that's the status of the relationship, and when things happen, they happen and that's fine. What Calleigh said at the end of the episode made it pretty clear that they're trying *not* to sleep together -- and not doing a very good job of it. It was a pretty optimistic convo, IMO -- they're going to table the discussion until they're alone, and I think their faces made it pretty clear that there was probably going to be a lot more than discussion happening if they ended up alone together at one of their places. Also, the way Calleigh brought it up, and the need to talk about this thing that keeps happening, combined with the relatively light tone of the conversation, makes me think they're probably going to end up deciding to stop trying to fool themselves. They're obviously not able to be just friends anymore, and it looks like they can't stay away from each other either. Time to just accept that they want to be together, have have it, I say!