Mavis,
Just personal preference, maybe. My husband has gorgeous thick black hair and he's worn it long, short, and not at all, sometimes in cycles. I tell him what I like best (long) and leave it at that -- I don't own him or his head, and if he likes it that way I've no right to change him. (I actually think it's a little exotically sexy when he goes bald for a while, but I don't tell him that)
No offense intended here (everyone's relationship is different), but if he withheld sex because MY hair was long or short or not blonde or too many gray strands or whatever, this would be a very, very short marriage indeed. MY head, I get to say what I do with it.
GL