Sexual funk (possible TMI)

My husband and I have always had the most amazing sex life since we met 5 years ago (been married for 3). We've gone through a lot and been long distance for the majority of our time. As of a few months ago we're finally geographically together on a regular basis (the way normal couples are), bought a house together, and completely settled down with our kids. As of late we've been having trouble in the bedroom... I've felt unattractive to him since he seems to rarely be aroused. It takes a lot for me to get him hard and I've been feeling terrible because I want sex so much more than he does right now. He always seems to be exhausted and has gone to the doctor to get checked out; he says he doesn't want to be this way because he does want me but his mind is just... Not there. It's a vicious cycle because he most likely feels emasculated by me pressing him/joking about sex so much, but I can't help it. It's been about two months like this and now, even when we do have sex... I'm not into it. I don't feel satisfied. I sneak off at night into another room to masturbate with my vibrator because I'm so dissatisfied :( Ladies, what should I do? I still find him ridiculously attractive, but I don't know what's going on. Help? What would you do?