My partner knew I was trans and considering transition a year before we got together. She was my first love, first kiss, first everything. And I was madly, hopelessly in love with her. Enough that I would have done just about anything to try to stay together.
We split 6 months before I started HRT. It was... brutal, and we have no contact with each other anymore. Took a long time to stem the bleeding from that, and even now it still kind of aches a bit to think about. Like an old break.
Wow, thanks Sarah, what an uplifting story right?!
I didn't date at all through transition. I was still a mess after the break up, and a mess from dealing with transition so... I let all that be. And then about a year after my SRS, I screwed up my nerves and turned one of my best friends into my girlfriend.
I don't think you can really fall in love the same way twice. Or at least that isn't how it worked for me. But that wrenching, desperate wanting is the same. Needing to be with her every moment I can steal. And she has a kindness and calmness in her that makes me feel not-broken. Like I'm a real person, for the first time.
And I would do it all again the same, even the worst, worst moments just to make sure I would get to this point, right now.
So even if it all breaks. Doesn't have to mean it stays that way. All the wisdom of my 30 years.

Best of luck, whichever way it goes.