I would wait if I were you. It could cause a lot of problems if you try to get into a relationship with him. There are millions of other guys out there that can also work for you. But if you are sure this guy is the right one for you, then you need to wait. If you truly love someone and don't want to hurt them, then you should be willing to "give sacrifices" and let them go their own way. Otherwise you could tie him down in a relationship that he may be uncomfortable with or unhappy in.
Find someone else to date. It might make him jealous. But if he's not jealous then just move on and find someone else.
If you like a guy and he has a girlfriend then you should back off and only try and be his friend.
If the boy has a girlfriend, find a guy that doesn't have a girlfriend.
wait
...
He has a girlfriend. So you butt out. It's not complicated.
you use his girlfriend like a ladder and jump over him
Well, its ok for them to hang out. If you trust her, then yes, if not then go with her. Like a double date.
You shouldn't flirt with him if he has a girlfriend.
Spy on him! A wife caught a guy redhanded giving nude photos of himself to his girlfriend.
You simply ask him.
you can tell him, or his girlfriend if you are friends with her
Yes.