It "bugs" the non-alcoholic partner because to that person quitting drinking is a no-brainer. Why would anyone choose alcohol over the good things in life? The answer is that they AREN'T "choosing" it, they are COMPELLED to drink. It's sort of like someone telling you that all you have to do is "choose" to quit breathing. That's how it feels when you are in the grip of alcoholism. It's impossible to imagine life (a happy one, anyway) without it.
Until an alcoholic feels personally desperate enough that he or she feels unable to go on with life as they know it, it is simply too hard to contemplate.
If he has only agreed to "try" because you argued him into it, I don't see a lot of hope for this situation.