My girlfriend [F/M23] and I [M24] broke up after dating for one year. They decided to start transitioning from female to male and we decided that our relationship would make the transition process a lot more difficult. I'm looking for some perspective.

DISCLAIMER: to the trans and genderqueer people reading this I apologize in advanced if I mess up the pronouns. I'm relatively new to interacting with this aspect of humanity so for consistency's sake I will refer to my ex-girlfriend (partner?) using the singular they.

A little over a year ago my girlfriend and I met and started dating. Things started off amazing. I was 23 at the time and had never been in a relationship before (meaning that this is also my first breakup). We got along together really well and had a tonne of stuff in common (our sense of humour, our generally nerdy interests, etc).

Early on in the relationship they told me that they identified as genderqueer. The definition they gave me was that it was someone who felt that they were neither male or female but something in between or outside it all together. This was something I was able to wrap my head around. I interpreted this at the time that they were something like a tomboy who was also frustrated with the roles society placed on women so I was able to accept it without much issue.

Flash forward until about two months ago. They tell me that they have been researching and discussing with their therapist about the possibility of testosterone therapy. Up until this point they had made no mention of transition. I took this as something that they were simply researching rather than actually planning on doing.

Flash forward again until a few days ago. The two of us sit down and they tell me that they plan to start transitioning with the intent to eventually become fully male (hormone therapy, name change, possible reconstructive surgery etc). Then the discussion of the future of our relationship comes up. I am a fully heterosexual male who knows that I have never had any attraction to the same sex whatsoever. As such we de decided to call the relationship off. More accurately, they wanted to continue trying but I felt that the relationship would eventually do more hard than good to both of us.

I had had some previous exposure to the trans community mostly through gay friends and reddit (I lurked twoXchromosomes a lot before it was made a default subreddit). My rational for calling of the relationship was that my desire for them to remain female would make the transition process infinitely more difficult for both of us. Either I would always secretly view my partner as female and then they would be miserable or if I did come to view my partner as male I would lose a lot of my attraction and then I would be miserably. Anything short of 100 percent support would just lead to eventual resentment, even if they decided to eventually stop the transition (which I don't think is very likely).

That being said I still feel terrible about the entire thing. Logically I think I made the right decision but emotionally I still feel I'm abandoning someone I love. Transitioning is an incredible difficult process and I know that I they will need a lot of support. I just don't think I'm able to provide it. Compounded to my guilt is that my girlfriend now also has to deal with the stress of transitioning as well as dealing with a break up.

In addition to everything else this is also my first breakup so I don't really know how to process what I'm going through. I've tried going to my friends but I feel like they are having a difficult time empathising with what I'm going through (I realize that this is a somewhat unconventional reason for a break up).

I am not not really looking for validation or sympathy, I think I'm more so looking for perspective. My friends and family have been supportive but I feel that they just don't understand the issues involved. If any redditors have gone through a similar situation I would love to hear about it. I would also like to hear if any trans people have experienced this from the other side and would like to share their thoughts. I think just knowing that someone else has gone through something similar would be a big help.

TL;DR; my girlfriend decided to start transitioning from female to male and I decided to call off the relationship. I didn't think I would be able to provide the support they needed and that both of us would become unhappy. I am looking for anyone who has gone through something similar to offer their input. Thanks.

Edit: now that I see this posted I am sorry for the giant wall of text...