April, let me make two points, trying to be realistic here.
1. I know transwomen, especially younger ones (under 40), who are in loving relationships even though they are pre-op.
2. The number I know and have encountered online is small.
It's that second point I think we need to be realistic about, ok? There is always the potential you will meet "Mr. Right" and that he will be patient with you and walk with you through this journey until you and he are finally content together.
But on a practical note, most of westernized civilization tends to be very gender binary rigid and most cisgender men and women have preconceptions and misunderstandings about what being trans means, and therefore they leap to conclusions in which they exclude themselves from even considering a pre-op transwoman.
Short but practical answer? Finding someone when you are pre-op is possible but a lot rarer than we would wish, and I think we need to keep that in mind and be realistic as we approach that personal need to finding our significant other.
P.S. My own experience over 50 is far, far worse, especially living in a state like Texas. The good guys are out there but they are very rare.