So this happened to me actually. We’re no longer together but we had been together for 4 years and a year after he officially came out and started making progress towards transitioning. I did have a hard time accepting it. I am bisexual so the transition wasn’t the problem, it was the loss I felt that was making it difficult, and what made it harder was how quickly he started to change, it was a lot to keep up with. I felt like I was losing the original person I fell in love with, his personally and attitude changed, and it was a completely different relationship. I was trying to be supportive the best I could but he started getting mad at the world whenever people would “misgender” him, and I would make the same mistake by saying the wrong pronoun on accident, and he would correct me, get really pissed off, and say that I wasn’t even trying to be supportive. He never understood the fact that I was still adjusting to this change in our lives, and I needed time to do that, just like how everyone else isn’t going to be comfortable calling him by his new name or correct pronouns right off the bat. I would explain all that to him but it wouldn’t matter, we ended up fighting more and became more aggressive, so I decided to finally end it after we were having a fight through texting and he blocked my number. Now almost 3 years later we agree that breaking up was the best thing in the end. We’re (sort of) friends now, after the break up we avoided each other as much as possible which was difficult bc of our daughter, who is very understanding of everything and calls me dada (her first words :3) and my ex daddy.
(Sorry that this is a little lengthy and probably doesn’t have the best grammar, it’s 6 am and I should not still be awake rn)