Talk to her about it...if she doesn't listen then break up with her.
Yes, it is as normal for her as it would be for anyone else.
She would have to put that person's name on the registration. The other person (or girlfriend) would have to pay for the insurance.
he would probably leave you because he likes someone else but he would be stupid to leave his sweet and caring girlfriend
Be honest with your girlfriend. I have a friend who has a girlfriend but he is in love with his best friend, the longer you leave it then the harder it will get because your feelings for this 'someone else' will not disappear. Depending on how long you have been with your girlfriend it is the time to think whether you will later regret your actions or have any feelings for your current girlfriend. But in this case honesty is the best policy because no girl would or should be lied to if you are in love with someone else then tell your girl!
To me, I say yes. I do not really see the point of having a girlfriend if you do not date. What else would you do? Like in grade school when you "have a boyfriend/girlfriend" and do not do anything, I find that pointless. So I say yes.
his girlfriend
No.
When a guy says he would date you if he didn't have a girlfriend, he is being nice and letting you know that he is already taken and that you would be someone that he would consider dating if he wasn't already with someone else.
She likes someone else, or she cheated on you.
Justin Bieber has a girlfriend so it is unlikely he would go on a date with someone else.
This may sound harsh, but I would dump the girl and find someone else.
With sincerity. How else.