Could you ever fall in love with someone outside your sexuality?

One narrative trope I really like is the whole "It's Okay If It's You" thing. So, do you think you could ever see yourself falling for that one person who makes you question your sexuality, even though you never thought of other people of that gender that way before? Straights, could you be in a relationship with someone of your own gender? Gays, could you ever go along the straight and narrow for that one relationship?

As a bisexual, I kind of find the question fascinating, because all genitals are yummy.

And easy mode: the person is transgender, so no one needs to know but you. And even easier mode (for guys), they're post op, so you don't even have to deal with dicks (sorry ladies, vaginaplasty is easier than... peniplasty? So the dicks aren't as good).