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This is a pretty serious situation.
I hate to say it, but I have been in this situation. But they were convinced that I was bisexual or that I used to be gay. I guess it was obvious that I liked women.
The problem here is that she is not accepting the fact that you are straight. In my opinion, once she starts doubting your heterosexuality like this, she’s never going to stop. She will never believe you are straight no matter how many times you tell her. They simply never change their minds about this.
Furthermore, it might be insulting. Many straight men are insulted by the idea that people, especially women and in particular their girlfriends, think they are gay. If this is how you feel, she is insulting you all the time you are with her.
Relationships with women need a couple of things to be successful.
There are two deal-killers.
First, she has to be OK with your masculine style. If she feels you are lacking in masculinity and she dislikes this, the relationship is over. It will never work well.
Second is she has to accept your sexual orientation and be OK with it. If you are straight, she has to believe that. She can’t be wondering if you are gay or bi. If you are bisexual, she absolutely needs to be OK with that. If she’s not, it will never work. In other words, your view of your sexual orientation and hers need to line up.
This also looks very bad for the relationship. I don’t see how this relationship works if she keeps this black cloud of your being gay over her head all the time. It’s going to affect her opinion of you, and not in a good way.
I realize that you are engaged, but I would get out of this relationship pronto. Either that or issue her an ultimatum that she either believes you are straight or you end the engagement, but in that case, I bet she would just agree to drop it and keep on wondering.
My advice is to end the engagement. This is so serious a matter that I do not see how this ends well.
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