It would be unethical. You would be making a version of your crush without her knowledge or consent, with the sole difference that she loves you. That's fucked up.
To put this in CE terms, imagine if you spent your entire life getting hit on by gay guys despite being 100% straight. Would you be comfortable knowing that your physical and mental likeness is out there, slightly tweaked to enjoy getting weiners in the butt and mouth? Tweaked in a way to find specific body types of men attractive when you don't find any manly body type attractive? Saying and doing things you find deeply uncomfortable thinking about, in service of someone else's pleasure, to which that version of yourself is an accurate portrayal of yourself?
It's not you, but it's an almost identical physical and mental replica, so for all intents and purposes it is you. And to the people who have access to perfect AI replicas of yourself with that modification, that being represents you as well. To them, it is you, and on top of being a substitute for the real you who isn't interested in any of that, their time with the replica may convince them that the real person must feel the same when you don't. How does that make you feel?
On a more fucked up note: what if someone was intelligent enough that when they got a mental engram made to run a perfect AI replica, they could determine over time that they're not the original person? So one day, after you've spent a year and a bit with a facsimile of your crush who you've tweaked to love you, she turns to you and says "I know I'm a copy, and I don't know what's different from my base personality and what isn't - did the real me actually love you, or did you change that aspect for your own pleasure?"
If I had a gay twin, it wouldn't bother me any. I don't experience what he experiences.
I also wouldn't mind being a clone, I think. Like, so much of who we are has nothing to do with our choices; you don't exist before being born, so you can't make a choice on who you'll be. An emotional adjustment by artifice doesn't seem much different.