Your post is a little vague. In short, depression is best addressed by a professional. With that said, the depressed person NEEDS to want to get help for the depression and NEEDS to do everything they can to make this happen.
For some, telling their story is too hard to do, so they keep repressing the issue and the depression lingers on or manifests itself into something bigger down the line. Some people are in complete denial. Some people are afraid of being labeled as weak.....
If the person cannot admit to a problem, they cannot get to the root of the depression.
Hi. Well, some more details would sure help. Is he admitting his depression and acknowledging that it is contributing to problems? Is it problems between the two of you or in general? What is his willingness to get help?