Disclaimer: We're not very religious people, and she does not really think that gays/lesbians are of the devil. Thank you.
Now, I know being bisexual he still likes girls, but what I'm afraid of is, a) he was missing something from women/men that he went looking for in the opposite. I say "women/men" because who knows if he was attracted to women before men or vice versa, b) if he's only saying "bisexual" to make it more socially accepted, when really he's gay. Also that would make me a really sad panda, and c) if in the future he'll choose to be with men.
Granted, I shouldn't really care regardless because we'll never be together (thank you, cruel universe), but I seriously didn't see this coming at all and so, let us mourn.