I have had my hair straightened in the past, and recently learned to love my natural hair. I haven't had bad feedback from guys about curly hair. Maybe my experience would be different if I were in high school, but I've only ever had positive feedback since wearing my hair curly. I feel better about my hair, and my image, now, than when I used to straighten my hair.
I think my boyfriend at first prefered it straight (in infer this because I asked him once
about my hair, when it was styled curly for the first time, if he liked it. I think he said "Both ways look great, but I prefer it straight." Since then he's totally changed his mind though. He tells me now what he loves my hair this way. I don't think he really cares though, to be quite honest. It's just hair to him. I have to bug him to get feedback of any kind. He still thinks my hair looks nice on my BAD hairdays. He doesn't notice a difference, so I'm starting to realise that his opinion doesn't sway me that much.
Anyway..what I'm trying to say is that my hair has probably grown on him. He's done different things with his hair that I privately though were awful, but they've grown on me too. New things require an adjustment phase.
That being said...if someone met me, dated me, and THEN decided to pick appart features that they didn't like, I'd be in the market for a new guy! I just could never put up with something like that. It would be too hurtful, and that isn't someone who I could live with.