I can't see Vincent and Rachel hitching up, I reckon that they really are just "very good friends". Being in such close proximity must bond them but I don't imagine there will have been any exchange of bodily fluids.
As for her boyfriend tho'. Nah, no way will that wedding happen. Rachel's grown up a lot in the past few weeks and he so-called fiancee is too much of a wet rag for her now. Good luck to the girl, ditch the moody sod and get someone new.
As for Vincent, he's Italian, for heaven's sake, they're like that. He grew up in a culture where flirting and such is a part of daily life, it doesn't mean that he's actually doing anything.