[spoilers] Ros, Fiona or Anna?

[Kirayuki]

I think they touched slightly on Jo/Zaf. They apparently cut a scene where Jo said yes to moving in with him at one point. I've also heard that Jo had a sort-of crush on Adam to start off with and someone said 'you do know he's married?' to her. Also cut though i think. (Probably heard it in the commentaries or something).
However i do think they subtly went there regardless, as Jo only trusted Adam after the whole S6 ending event and how shook up she was about Zaf early that series.

Jo's reaction to Ben's death was probably under-played and i agree with you on that one. They started off as something then forgot about it. After he died she had about one line to do with it and it was swept under the carpet.

I do see what you mean about the relationships in the show though.
Lucas/Sarah is one of the worst for me but I really think that the worst was possibly Tom/Vicky. That was a total waste of time.
I also think that Adam/Ros could have worked alot better if it wasn't so rushed and skimmed over in the one series. Fiona was safe i think.

Hope that makes sense and isn't just rambling.