>>16403356The question is simple:
Are you friends with her BF?
if the answer is yes then don't do it because it'd be a dick move and you'd be losing a friend for what? 2 minutes of blowjob?
If the answer is no then go for it, the girl is still a person capable of making her own choices, she's not owned by her BF so if she wants to go and blow another guy it's her decision and therefore her responsibility.
Of course she could pretend you forced her when her BF finds out or her BF can just be an idiot and think it's your fault for accepting her invitation. I suggest you get some prove that she initiated it or that it's fully consensual so you won't get in trouble if shit hits the fan.
>>16403449I can't help you on the relationship end because I don't know how do with that sort of thing.