Because he is a gay man
No, although a straight man can love a gay man as a best friend.
Yes, because I was that Gay man she fell in love with.
If he's the right man, he'll fall in love with you. If not, move on.
Yes, it's possible, just like a straight man could fall in love with a lesbian woman.
Definitely. Falling in love has nothing to do with sexual attraction.
No. Being gay is genetic. If your straight it's nearly impossible.
She can possibly make him fall in love with her by being his friend, but she will never make him attracted to her.
Yes, the degree in which a gay man may love the woman may vary, but yes a gay man can love a woman just like any other person. I fell in love with a Woman and was about to propose, unfortunately (or maybe fortunately, depending on how you look at it) it didn't happen. I still loved her for years later and today still hold special feelings for her, in the long run it was better that I didn't marry her. Being a Gay Man doesn't mean you can't fall in love with the opposite sex, you can't "make" your heart fall in or out of love, it happens regardless. Though in all honesty it is less common for a Gay Man to fall in LOVE with a woman, but we still love those we love.
Gay men fall in love with other men. Liking anal sex with a man can be a sign of it but only you know that.
No, it's more likely that he has other issues, such as commitment issues.
People experiment sexually all the time but what makes you gay, straight or bi is who you fall in love with so you really have to trust him on his word.