Cleopat,
Sounds like a situation I've been in.
Speaking from my own experience, no one could/can make me stop, no matter what, unless I want to. Initially, I considered myself, which I may have been at the time, a "high functioning" alcoholic and it had very little impact in various aspects of my life. But I've slowly been regressing over the months and years where it has been, in a big way. Personal relationships have started to erode, my career is faltering, my health is now taking a battering, and now it's recently gotten me into trouble with the law. All the while I too said "I'm fine, I don't have a large problem.. Not like others!"
My girlfriend has been very supportive and caring, almost enabling me at times. I know she feels hopeless at times, and it pains me. I know in my heart of hearts I need to stop, and sometimes I go for a few weeks.. But like the person you're with, once I have that one drink it's game on, usually until I'm black out drunk..
I've done and said similar stuff.. Hiding bottles and saying no more hard stuff, just beer... But eventually I revert to my increasingly self-destructive ways. Hell, even right now I'm going through some withdrawals from my last bender that ended a couple days ago. I feel horrible, physically/mentally, haven't slept for nearly 2 days and am ashamed I disappointed loved ones yet again.. This wasn't a scenario for me just 2 years ago, where I'd maybe just have a headache and could limit myself.
There's no easy answer or advice I can say offer. It's really going to be up to him when he really wants to quit.
Perhaps attending al-anon meetings? Speaking with people that are living through this from the same experience would be helpful in coping.
I hope you find a resolution, good luck.