Mark :
Would keep quiet about it and seem like nothing was wrong. Yet he'd closely watch the guys movements and if something was really worrying him or aggravating him he'd be vocal about it and get the both of you out of the situation or make the guy leave.
Taeil :
Very affectionate. Not in the all over your body way but in the sense that he'll call you 'babe' or 'honey' in front of the guy hoping that the guy would get the fact that you're taken. Other than that he wouldn't be super possessive he just doesn't want this man by his love any longer.
Haechan :
Savage Haechan is turned on. Hopefully he won't actually pick a fight but he sure would push the guys buttons. You'd probably have to tell him to stop at one point because one he was embarassing you and second the guy got it by now. The only reason he would do this though is because he cares for you so much.
