To be honest? It comes down to age and personality. Most relationships fail. Simple fact. The younger you are, the more likely the relationship will fail. People are rapidly changing when they are under 25 and constantly rediscovering who they are, so most of the bonds we make to people, places and things in this life stage are temporary. That's not to say it's not worth it. Or that it's not possible. But it's very relevant when you're discussing big things like orientation.
I am 31, demiromantic and asexual FTM. My b/f is heterosexual and cis and met me when I still lived as female and identified as bisexual. This absolutely would have never worked when we were younger. We both have grown and developed as people and because of our mutual respect for each other, our friendship comes first. When I admitted that I have no interest in sex and that it was traumatic for me, he understood this. Not only because he's my boyfriend, but because he respects me as a person and wants my happiness as a friend. When he admitted that he needed sex in his life, we discussed it maturely and decided that polyamory would work for us. Now we are looking at the possibility of my becoming involved with a woman I have known for a long time and developed feelings for.
The specifics of our relationship and the labels I could throw on it are complex, confusing to outsiders and what most people would consider downright "weird". But it works for us because we make it work. Put your partner's needs first. Stop trying to shove labels into your relationships. Honor your feelings and be honest with each other. Don't do these things because you really really want to make the relationship work, do them because you both deserve to be heard and respected. Sometimes things just don't work out, but follow those simple rules and it will always end for the better. Whether you are with her or not.
