Thanks for your frank story. Several things could be going on. At 37 he could have low testosterone or some other male sexual health problem. You mention several things it "could be" including low T (The affairs. My weight gain. My facial hair. Maybe I smell bad. Maybe I'm no good in bed. Maybe he's just tired from work. Maybe that MASH rerun episode is his favorite. Maybe he's gay but won't admit it. Maybe he's into something really kinky but is too ashamed to ask for it. Maybe he gets all he needs from jerking off to porn. Maybe he was abused. Maybe he has low testosterone. Maybe he needs Viagra. Maybe he's just asexual. Maybe this, maybe that..). Seems to me he needs to deal with identifying the the root causes; if he doesn't your frustration (emotional as well as sexual) will just get worse. I don't consider sex in a marriage a trivial thing. I'm 57, have low T, but with testosterone supplements and Levitra we still enjoy sex a couple times a week. Hope he is able to get over his fear of whatever is keeping him from getting checked out medically. Best to you.