Sorry I have no input on the effects of T on a person. I can say that I can relate to your fears. My SO is MTF and has mentioned before having a slight curiosity about being with a male, although has never been with one as of yet. Sometimes I worry about that but then I tell myself we'll cross that bridge when we get to it. I don't know what will happen if anything, so there's no use for me to stress about it at this point. We are deeply devoted to each other, and completely happy in our relationship. That's what's important.