Wife is concerned about my orientation during transition...

I'm not trans but I am gay and I have a strong belief that you are born with your sexuality you didn't learn it or pick it up. I can understand how being born in the wrong body could confuse things a little. I honestly think communication is the best way to go. Constantly tell your wife how you feel about her all through your transition and maybe eventually she'll become secure in the knowledge that you may have changed your body, but you are and what you feel about her will never change. I don't think testosterone will make you like men. If it did affect sexuality you'd think it would do the opposite. I just did a quick minute of reasearch and there are on line support groups and CHatrooms for spouses of transgender people maybe you could look in to them more and suggest some to your wife. Her fears seem to based on one persons experience maybe talking to others with different experiences might help.

 

This happens a LOT. Many many trans guys experience changes like your friend did and go from mostly or exclusively dating women to mostly or exclusively dating men.

That being said, though individual experiences may vary and are still valid, I don't personally believe that sexual orientations are actually changing (or at least not 180ing). I just think it's mostly just that it is easier and less dysphoric for a pre-t, or even pre-out, trans guy to be with women for a variety of reasons. First, it's easy to be confused when trying to figure out your gender and think that living as a masc/butch/androgynous lesbian is the answer to your gender feels. Similarly, many people know that they are queer before they know exactly what type of queer, so dating women (when presenting as a woman) is an obvious choice. Secondly, if you're still living/presenting as female, dating a man, no matter how attracted to them you might actually be, leads to a heterosexual man and woman dating and sexual dynamic. It's easy to see why this is more invalidating of a man's, even as yet unacknowledged, identity as compared to a homosexual woman and woman dynamic. Finally, there's a big problem of being a queer man living/presenting as a woman: Other gay men aren't going to give you a second look.

Once transitioning, all of these issues resolve themselves and people are more able to openly live out their true sexual orientation, whatever that may be. So for guys who were always gay/queer, they are finally able to pursue men and it may look to outsiders that their sexual orientation has changed. However, guys who have always dated women because they have always been legitimately only been attracted to women are unlikely to experience much of a difference.

All that being said, I recommend making sure you do some good soul searching and introspection before you assure your wife that you are in the latter category. Our minds can be really good at tricking ourselves into believing what we want/need to believe to survive. If you have really considered the matter and are confident that your attraction to women is true and not in part a defense mechanism, I think you and your wife can both rest easy.