There's only one thing worse than being in the midst of a depression. That is being in a relationship with someone who is displaying signs of depression. Watching them go through the stages of depression darkness are tough. Many relationships end as a result of this because it begins to take a toll on both individuals. One of the effects of depression is irrational thoughts. These thoughts blind the individual to the truth of what's around them. They only see the negative, not the positive, things. But depression can be reversed with a strong relationship.
Your presence in the midst of the struggle with depression carries more weight than it appears at the time. Many times the depressed person appears to push you to leave them, yet that's the last thing they really want. They want you to be there and even to help them come out of 'the hole' if you can.
The first step you can take to help them is to get some education. Begin to investigate and research their mental disorder. Try to assess the cause. They may have lost a job and are unsure of how they'll care for themselves and their family. They may be feeling like a failure and withdrawing seems easier than facing a rejecting world. They may have lost a loved one and are feeling guilty about something concerning that individual. Several things may have happened all at once leaving them feeling overwhelmed and their only coping mechanism is to turn inward. There are lots of reasons they're in a state of depression. Once it has started, it can certainly snowball even if you're in a strong relationship.
The second step is to take care of yourself, as well as your partner, in this situation. Depression can be contagious. You don't want to start exhibiting the same signs as you're seeing in your mate. If you do, don't waste any time seeing a counselor or psychologist. If both of you are in a state of depression, no one will be available to pull either of you out. When you feel yourself becoming too consumed by the overall weight of the depression of your partner, take a step back and regroup. You must preserve your own mental health if you are to be available for your mate.
The failure of previous relationships can sometimes contribute to depression. When one relationship has failed, the individual may assume that all subsequent relationships are doomed, as well. Then they begin to subconsciously do things to fulfill the prophecy of all doomed relationships. If this is your situation, you need to get some relationship counseling immediately. Seek relationship advice from trained professionals as much as you possibly can.
Lastly, and most importantly, don't give up. You have to know within yourself that you are making a difference and that you are helping them, no matter what it actually looks like. There are only a few things more powerful than what can result from the unified efforts in a strong relationship. Depression may be hard to overcome, but it can be done when the one you love depends on you. I'm a living witness depression can be reversed with a strong relationship.