Not technically speaking, but if you wanted to divorce him it would be good grounds. It's a good idea to communicate with your husband and see what is wrong. It could be something physical and at 40 plus men DO go through 'Andropause' a type of menopause, and he could be semi depressed, moody, even have hot flashes. See if he'll go to the doctor for a good check up and have his Testosterone checked out as well. A T3/T4 thyroid test is a good idea too.
Could be the husband has a sleeping disorder and wishes not to disturb his mate. Sleep Apnea is more common than people realize - A C-PAP machine is then used to assist the person in breathing correctly during sleep. Cause for divorce ... no way, as many older couples (in their 80's) don't sleep together either.