You essentially just repeated the same definition I gave you. I'm not wrong. Being gay is about who you prefer to be in sexual relationships with. I don't know how you don't understand that, but that is the definition. But then, maybe you don't actually understand the words of the definition that you're typing to me. I don't know.
Being straight means you prefer to be in a relationship with a person of the opposite sex. In that respect, being straight is obviously about sex.
So is being gay.
So is being bisexual. Or pansexual for that matter, a label some people prefer over bisexual.
If sexual orientation weren't about who you prefer to be in a relationship with, because you're attracted to them, then it wouldn't be sexual orientation. We wouldn't also sometimes call it sexuality. It would be a different topic altogether, which I guess maybe this is for you.
But when I, and when almost all gay people say we're gay, we mean it's because we are oriented towards sex with people of the same sex.
It's about sex, and there's absolutely nothing wrong with that.
Sex is not shameful. There's nothing wrong with sex. The homophobes and religious moralizers are wrong about that. We don't have to play their game.