My Brother's relationship (what should I do)

My brother has went into the Army. Before boot camp ( I believe that's what they call it) his girlfriend told him that she will not marry him until she has graduated from college. At that she has not entered College yet and my brother has to pay for her to go to college. He got on base maybe a month or two ago. Come to find out she talks and flirts with other guys. He has an issue with that. They had this issue in the beginning of their relationship as well. He says him and her relationship is rocky. Young, dumb and in love! There has been many that told him they wouldn't ever last and she'll cheat...

I haven't been one of those people even though in the back of my head I find it very odd that he has to pay for her College just for a possibility of marriage. I let him know that I support any decision that he does just as long as he's happy. This girl though, I don't get a good feeling from her. Yet I don't want to say things to my brother of how I feel. He has enough of that from everyone else.

He will live on base and live pay as little as he can there. Everything else will go to her so she can go. I don't agree with him doing this at all! He "loves" her and that's why he is doing this. I've told him if they married each other then they will pay for her schooling. He's all for that as she refuses and tells him he has to pay for her College and after that she will marry him.