Help!

Ohkay so I've been with my bf for over 6 months we live together but he's out of town a lot for work. He works really long hours but when he comes home even after a good nights sleep if I try to have sex or mention having it he will say either no or later. Sometimes he says yes but falls asleep before we do. As soon as I offer him a blow Jon he immediately says yes.... I don't understand is he not attracted to me anymore? Or am I over thinking this