I don't think there is anything wrong with it. There's somebody for everybody
I personally don't have a preference. I used to be heavy 100lbs over weight from what would be considered the top end of my normal bmi for my height. When I married my hubby, he was super thin.
I had since lost 120lbs, and while I'm currently 15lbs above that (kids and holidays, haha), and my hubby outweighs me by a good 60-70lbs now. I find him just as, if not more attractive now than I did before.
J is super thin and I like him and his body for different reasons.