Well, I'm 38 so I think that's in between young and old. I've been married twice. I know I'm 100% heterosexual, attracted to guys as a woman. I like women, but more for friendship, I know I can't be in a relationship with one (even though I've pretty much spent most of my adult life trying to play that role). I succeeded in convincing myself and the women I was that it would work out, especially at the beginning of the relationships.
I truly know that I need a relationship with a guy to feel the intimacy (not talking about sex here, if you feel the same way, you know what I'm talking about (the holding hands, kissing, just feeling really close to someone)). I can't and have never been able to feel that with a woman. I mean, I know what a woman wants so it can be a little self-delusional, but I do know what I need to fulfill my innermost relationship needs. It was so confusing for a long time, it's like "how am I supposed to be able to have a fulfilling relationship if I need a guy and I'm a girl but I have a man's body?" Very confusing to say the least.
I have known this since my teens but I've never done anything about it. I've never really been afraid of a relationship with a guy as a guy, but it just doesn't feel right, it's hard to explain. I would be totally accepting of myself if I was a gay guy, but that's not what I am. I'm a heterosexual girl.
So, I am not sure about others, but here I am at 38 knowing that I want and need to be in a relationship with a guy to be happy. I'd rather never be in another relationship than be in another that left me unfulfilled and empty.