Sorry for what brings you here.
I was a daily drinker. I got married late in life, at 53. I was positive that getting married would turn me into a "normal" drinker. It didn't.
One morning, nine months into my marriage, after a night of uncontrolled drinking, I vowed to quit. Forever. My wife didn't deserve a drunk for a husband. So far, so good. So it is possible for your bf to turn this around.
But he has to want it. Has to want sobriety.
I think you need to think about what you will do if he doesn't.