Yes, ever since we lost the AllSpark, the Autobots have been in decline..
No, joking aside, I've never had a spark to begin with, depression was always stronger than any spark I might have had somewhere. I found my spark when I was 31. And I lost it when I was 33. I'm not taking about the love of my life now, about the person. I'm talking about the inner strength, the hope, the drive to achieve, to do something. I was part of something that gave me so much energy, so much happiness, so much to thrive for, that I could do anything. I was working hard, on my PhD, on my relationship, on myself, body and mind. And ever since he left, I'm in worse depression that I have ever had (I think, some days I think it's not my depression at all, but for the sake of argument, let's go with that here now). I have lost all drive, to do anything, at all. Groceries, laundry, eating, sleeping, all require too much energy to do.
As @CaptainT says, when you feel the spark slowly going out (for me about a period of 4-6weeks), it's a horrible feeling. Mine is still every now and then, but it's almost gone. But I think I welcome when it's fully extinguished. I think CtB will be very easy at this point. I believe my spark held my hopes for a better future and a fulfilled life. That's gone now.
Take care of yourself and be kind to yourself and others on your journey. I think if we all had more love and compassion for another as well as for ourselves, we could help nourish a lot of 'sparks', rather than letting them grow cold.