His wife has a younger sister is who my age, 23 (quite the age gap, I know). We are related technically, but not by blood in any way. We hung out when they got married, but thats it. Recently we met up one day and just caught up with one another, cordially, but I did get some more than just friendly vibes from her. We clearly both think one another are attractive. She always seems to like my instagram posts and recently she messaged me again and I don't know for sure, but I think she would be open to hanging out again.
Like I said before, she's pretty attractive. I guess what I'm trying to ask is, would it be okay if we hung out and ended up hooking up? Would that be weird and a for sure no no? We're not related in any way by blood. I'm originally against it but something tells me she really doesn't care and feels different about it.