I'm not married, but I feel my 5 year, live in girlfriend provides the same sense of soul crushing emptiness...
If I'm "lucky" we'll have sex once a week if she feels like it. I don't know if it's her or me or what... but for the past year or so, I don't much care either way. I might jerk it once or twice a month. I think my sex drive has taken a massive hit somewhere. =\
Maybe it's my job going to shit or the dwindling attraction in my relationship, but I rarely get excited about sex now. When we first got together, we'd have sex 2-3 times a day and I'd still tug on occasion. Now, I when look down at my dick even HE tells me he has a headache.