First off, you don't love girl A. You don't even really know her and you never went out with her. She isn't interested, so put her out of your mind and focus on others.
As for girl B, it sounds like she likes someone else, right? There is no way you are going to "win" her heart by doing things for her. That will make her just want to use you for attention to make her feel good.
It is not a bad thing if you are a good guy, but you have to have strength and belief in your yourself. Confidence is key. And don't be afraid. If you like someone, don't be afraid to tell them and ask them out. Don't write about it on facebook. Girls like guys who take the initiative and show interest in real life.
Personally, though, I would say to stop thinking about girl A or B and take another look at the rest of the girls around you. There has to be some other girls you wouldn't mind beginning a romantic relationship with.
Good luck.
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