I wish I had a pound for every women who has asked that.
And I wish I had a hundred for every year of my own life I have wasted in the past asking myself that question.
When you are young, it can be really difficult to believe that someone wont change if you explain enough about the effects of their behaviour on you, or other strategies.
I learned very much the hard way at 50 that Hot damn is right. As she says:
You accept that they do not want to change, and make your own decision as to where that leaves you.
Obviously step one is to explain how you feel and try to work with him to sort it out, if he is willing. You need to be very clear about what you are willing to accept, and live with, both with him, and more importantly, with yourself.
It may well work.
BUT he is just as likely to blame you, blame circumstances, and do or say anything other than change his behaviour. And you need to be clear with yourself, as above, because that is the confusing point at which it is easy to drift on for years, not seeing th wood for the trees and unsure who is to blame for what.
In which case Hotdamn's advice comes into the picture. You tell yourself that he doesnt want to change, or he doesnt want to enough, or he cant, but at any rate you cant live like that (assuming you cant).
I tried to for a few years, and failed miserably, making myself quite ill finally. It was only when I made plans to leave and he knew that I meant business that he got his act together.