It's really hard to say what causes a relapse. I relapsed twice after long periods of sobriety. I had worked really hard at recovery for a couple years, then gradually just got involved more in my life and figured I didn't have to work at it anymore. My life had changed, I felt no compulsion to drink. The first time I relapsed, was after going through a divorce. I got sober again for several years (again) but started getting social again as a single person. I fell in with some musicians who drank pretty heavily and figured maybe, since I wasn't living in a depressing marriage anymore, I could enjoy moderate drinking.
Of course, those were the "circumstances" (which are different for everyone), and sometimes they can trigger a relapse. But I think there's a deeper layer which is common to all of us, whether it's a matter of the wiring of our brains or a lack of coping skills, or a spiritual malady....... there's a part of us which is discontent. Oftentimes it's an underlying depression or anxiety disorder, or something simply like insomnia that starts a vicious cycle but once we become addicted, there will always be a part of us that desires "just one more drink." Even if we have no intentions to pick up again, at times it's hard to fight that impulse unless we're active in recovery.
So really, it could be anything, or nothing at all that caused your husband to relapse. I know this is a huge disappointment for you (and most likely for him). I hope it will show him that we can never take recovery for granted and I hope he chooses to stop right away and double his efforts. Maybe he'll be more willing to look at things honestly once he sobers up.
You have my thoughts and prayers........
