I've been married for well over 30 years and spent most of that time in one phase or another of depression. My wife experienced a lot of pain because of my behavior, and we came close to splitting up more than once. From reading dozens of stories online, including many sent to my blog, I know that what happened to us is not uncommon - though the ending is often less happy than it was for us.
The stories I read - mostly from women - tell of hurt, confusion, fear, anger and desperation at the sudden transformation they've seen in their partners. A loving spouse turns into an angry, withdrawn and sometimes violent person who blames his partner for causing the pain he feels. Most of the time, he refuses to say anything, other than words of abuse. Many isolate themselves, others actually leave for a time and return, some men leave for good. And they do everything they can to avoid looking deeply into themselves. I'm sorry to say I've been there, I've done that.
If you're going through this kind of agony with an intimate partner, I know from our experience that it is possible to survive and to restore a damaged relationship. But for us, it was by far the hardest and most demanding thing we've ever done, and there were many times when my wife was convinced there was no hope.
I found one book that was especially useful in understanding what can happen to relationships under the influence of depression. That is Terrence Real's I Don't Want to Talk About It. Taking stories from his therapy practice as well as his own life, he details this kind of behavior specifically in men. He calls it covert or hidden depression, and that fit well with my own experience.
For a great many years, I knew I had depression, but I thought that only meant I kept going through episodes of deep emotional bleakness. I did not realize how pervasive its effects could be in clouding and scattering my thinking, intensifying anxiety and stress, filling my mind with obsessive and even paranoid thoughts and completely destroying my self esteem. So I acted out, blamed my wife for what I felt until I could at last understand what depression really was.
Then it was no longer covert at all but out in the open - a part of my daily awareness. At that point, I could begin to deal with it, and at last there was hope for my marriage.
Julie Fast's Loving Someone with Bipolar Disorder is one of the best books I've found for understanding what my wife and I could do in order to save our relationship. Even though she writes about bipolar instead of depression, most of what she says is directly on point for other mood disorders. She focuses first on recognizing the illness and treating it - unlike many books which emphasize what the hurting spouse should and should not say or do. Her approach gives the big picture and helps the non-depressed partner avoid self-blame or imagine that she can bring about her partner's recovery.
The most important advice I could offer is to remember that you can't change your depressed partner. It has to start with him. He has to recognize the problem and seriously start treatment. You can't do that for him. After that there are many things you can do to help, but you also have to look out for yourself and get your own support.
It's possible for that loving partner to return and for two people to renew their closeness. It's hard, but I know it can be done.