As a nurse, surely you know that while depression can wax and wane with situations, it is not always situations that cause it. Sometimes, it just is.
My affair with depression began ten years before I even met late AH. I can't blame him for that. It comes and goes randomly, or semi-randomly. Last bout came on when I had to put the cat down. I could blame it on that, or just accept that the black dog (isn't that what Winston Churchill called his depression?) will follow me indefinitely. I actually like dogs, but would prefer to just visit someone else's, not own one. *Sigh*
Most medications have worked for me. (Welbutrin didn't) I'm on trazadone now, and it's a Godsend. Sleeping through the night is a good thing.
I have accepted the fact that my brain just works this way.