Treat her with respect, compliment her, be nice and happy, make her laugh and be an all around good guy - you can give her flowers and gifts if it is something that interests you as she would of course love it. ANSWER According to Robert A Heinlein, you should rub her feet
If you like a guy and he has a girlfriend then you should back off and only try and be his friend.
My girlfriend. Back away.
Yes
If you are dating then by definition you are his girlfriend.
You shouldn't have done anything with him knowing he has a girlfriend.
If you dont know who the guy is then you should find out before being jealous. But if you do know the guy then you should just go have a long talk with your girlfriend because if you are jealous, your girlfriend might just break up with you.
A guy doesn't have to have a girlfriend. If you want to that's ok. Nobody should have to force you or say that you should have a girlfriend. It's YOUR choice.but if you want to have sex than you should have a girl friend.
tell his girlfriend
No, it is very wrong.
As long as the 'girlfriend' isn't your friend.
He has a girlfriend. So you butt out. It's not complicated.
Tell him that it is very impolite. Make him understand that she is your girlfriend and he should stop undressing her with his eyes.