Yeah, I agree. You can't stop yourself from having feelings for someone. I've definitely had feelings before for guys that had either girlfriends or were married.

I think peoples reactions of "but he has a gf/wife..." is probably because it's kinda pointless to have a crush on someone who is taken, if there is likely no possibility of anything happening between you and that person if they are in a committed relationship.

It's kinda like setting yourself up for being hurt. Ya know? Does that make sense?

Most people get crushes on people who are single, that way you can develop a relationship with them.

ETA: And there is a big difference between finding a taken person attractive and having feelings for them. You can find someone attractive without having feelings for them.