Is it normal that i am obsessed with my husband's ass?

I have an obsession with my husband's ass that keeps getting more intense. I'm not sure if it's normal or even healthy. I have a strap on and like to pound him in the butt (he is willing but not thrilled), I also like to stick my fingers and tongue up there and squeeze and touch his ass as often as possible, I can hardly control myself in public and take his pants off whenever we are alone. I cum just from having him smother my face with it, and lately I've been freaking out (in a good way) over the idea of him having sex with another man, despite him being completely 100% straight. Is it normal to like his ass so much, I mean especially as a girl?