About halfway through I saw the author and immediately knew what the dilemma would be. For me there are a couple of issues. First, I don't think I'd be fooled. I've seen some convincing trans girls, sometimes even thought they were cute, but in person, you can tell. At the very least, the voice is always a dead giveaway, it just sounds male, and kills the attraction instantly for me. But lets say somehow this happened, and I was fooled up to this point. Even if I could forget that she lied to me, I can't accept that she doesn't have a real female reproductive system. I want to have vaginal intercourse, but even if she got the operation, I also want to have kids. And not by adoption, but through actual procreation. Fast forward a few decades, maybe centuries, and I think technology might advance to the point where it's truly possible to change one's sex completely. If that ever became possible, and she looked, sounded, talked, acted, and thought like a girl, and was capable of pregnancy, then yes, I'd go for her, regardless of her past. So to answer what I'd do in the situation, well, assuming I had the feelings you described, I'd be quite torn, but I'd break it off. I wouldn't want to marry her, or even have sex. I'd probably lose all sexual attraction to her, but since we were so close, I'd probably remain good friends with her and care about her a lot, support her through the operation, and cheer her on in finding a guy that would want her.