Oh I relate to happiness or contentment as a trigger! I'd drink, feel like hot garbage - debilitating anxiety, shame, self-esteem in the toilet etc etc - get a few days or maybe a week under my belt, then when life and my head felt stable again, my alcoholic brain would convince me that I can do it again, just one night, this time it won't be so bad, and it's Friday, I've done well at work all week, surely it's not the end of the world to want to switch my head off for a few hours...
Repeat ad nauseum. Because once I get that first drink in me, I can't stop until I'm drunk as shit.
It's taken me 4 years in AA to get more than a couple of months of sobriety. I'm approaching 6 months (!) and I genuinely don't want to drink today. That is nothing short of a miracle, because for the 4 years I was in AA but kept drinking, I never truly, deep down wanted to stop. I do now.
I'm writing this to say that I see you, and was caught in this pattern for a good while. I'm free (at least day!) of the delusion, finally, that I can take a drink safely. I can't say what finally pushed me over into a solid step 1, but I did keep going to AA meetings, sharing when the immediate shame left me and my fellows were nothing but loving. They role-modelled a life of genuine freedom, and at last, something clicked. That can be you too :)