Agree with both responses above mine. Counseling can
work, but isn't guaranteed to work. There are a lot of variables - you have to find the right counselor that works with both your personalities, and both people have to be dedicated (and willing) to work on their own part in the issues.
I also think that even if only one partner is willing to go to counseling and the other isn't... it's still worth it for the 1 partner to go. As that person gets healthier it's possible the other partner will change their mind, and will want to work on things too. But even if they don't, at least the 1 partner will be healthier and in a better place.