Re: how long to stay in therapy?
We gave it a shot for about three months. There were no improvements, and my DH wouldn't talk or do the homework. Then one day we forgot an appointment, and he never brought it up, or said one thing about how our marriage was going. At that point I knew he didn't want to fix our marriage (versus having a hard time talking about feelings and such), so after waiting a couple more months for him to say something, anything, I told him it's over. He didn't yell or beg, he just started working on the mechanics - moving, checking accounts, etc.
So, if he's not talking you can only read his behavior. Don't sit around miserable another three months waiting for magic to happen like I did. I worked through the things holding me back - kids, religion, social stigmas, etc, and now know divorce is the right thing to do. Not the easy thing, but the right thing.