Found this a while back and I use it to try to explain depression to those not afflicted.
My depression is not always triggered by an event. I refer to them as down cycles and have told those close to me to watch for changes in my eating and sleeping pattern.
It is indicative of a depressive episode. I wanted my better half to understand it was not her. It was not anything. It was, well...you can't hide from the inside.
Understanding myself and explaining what I needed, just be there...hold me...hug me...I may even push you away hoping you will stay anyway. Give your loved ones the piece to the puzzle.
Be honest with yourself and them.
No one knows you better than you. I don't know why I am this way. But I know I don't want to be alone even when I act like I do.