WW- the changes in your brain due to depression might have altered your wants, needs etc but I would also say your Wife has had to change in this same way too. Her brain may be hard wired now as a care giver so she too has lost herself. If you could both work on finding your true selves maybe the spark could return. I think this is the case with me and the ex- I became someone I'm not (a care giver) not a lover I had to adapt to my partners depression otherswise the old me would have left her 2 yrs ago. Now I'm finding myself again - I saw the ex once recently it was probably the closer we have been in a long time. I think it's too late now for us ex wants some excitement With someone else and frankly she doesn't recognise that she needs to commit to her mental health so things wouldn't change with us. But I'm going to continue to find myself again.