Maybe. With me it's on and off. Increased blood flow for growing that baby has an interesting side effect that dh enjoys.
Although I think my times of uninterest are when I'd dead tired and still have dishes to wash and laundry to fold and have been holding my poop until the boys go to bed (my body takes it's time - I have to hang out on the throne for at least 15 minutes usually - kids don't allow that in the middle of the day)
. If he's really desperate, he'll pitch in and do dishes and help get the kids to bed. Otherwise, yeah, exhausted pregnant woman.