Personally, I don't mind Marco's interactions with Kelly. If anything, I find it nice that he found a new sense of comradeship with someone who went through similar heartache. Maybe shipping them together immediately is a stretch, but I do appreciate their dynamic.
It’s good to see that Marco might have had, even just for a single episode shouldn’t she have a role like that anymore, a friend to talk about his problems, even if in a very indirect way, since he clearly can’t do that with the two people he’s the closest with - Star and Tom. I’m just a bit concerned by the “teasing” tones the final scene of the episode had (that can fit normal friendship as well, but given the standards of TV show they were very ship-charged), since as I said (again, ready to eat back my own words should the show manage to develop things in a realistic and meaningful way!) I can’t see how Marco and Kelly interacting romantically could add anything to the show but more “filler drama”.
If it’s just friendship we’re talking about, we all welcome it.