I do not think our partners can focus on anything but themselves while in a MDE.  With my husband, it takes so much out of him just to make it through the day, he doesn't have the energy to do anything more than that.  The times he could see the unmistakable evidence (me crying or a very emotional fight/discussion) that he hurt me, he would suggest leaving because he didn't want to hurt me & thought I'd be better off without him.

I used to think he owes me big after this or he should be thankful I'm sticking by him.  Not anymore.  If the situation were reversed, I would not want to feel indebted to my husband.

I do know he appreciates me & gets to a small degree what I am going through.  He is unable to vocalize it during the d, but can as he starts to get better.  Here is a small exerpt from an e-mail he sent his family (& copied me) explaining his d

The more we learn about depression, the more we realize what a sneaky and destructive disease this is.  I have to give my wife many, many kudos for sticking with me through all of this.  I have, at many times, been mean, nasty, cold, and many other things, but she has persevered; doing what she can to keep our family together while conducting her own research.   The challenge now is undoing all of the negative things that have happened, whether my fault or not, over the last several (5-6) years.  But, as she says, it took us years to get into this mess, it will take some time to get us out of it.  Unfortunately, I was such a _____ to deal with through all of this.

I was pretty much a non-functioning member of the family for much of the past five years. My wife had to do pretty much everything. The only time I really helped is when we had company at our house.  Somehow, I was able to hide what I was feeling and going through from all but my immediate family.  My wife's focus was mostly on keeping our marriage intact & shielding the kids from the Depression as much as possible. We are lucky that we are still together, and it is only through her perseverance and my innate sense of commitment that we are. My Depression caused me to do almost unforgivable things. She was dealing with the fallout the Depression caused. 
Unfortunately, I think too many people do not express appreciation or thanks to spouses, children, coworkers, friends, etc.  One huge positive that my husband & I have both gained as a result of his d is an appreciation for each other & the good times & people in our lives.  Both my husband & I make a huge effort not to take each other (or anyone else for that matter) for granted any more.  We go out of our way to praise each other, our children & other people in our lives.