You do seem to meet some of the DSM5 criteria for depression.
40 is the time of life when we are most prone to look back on our lives to see what we have achieved. Asking those hard and difficult questons about life in general.
Is this really it? Who am I? What does this all mean?
The busier we are with life, socialising, work and family the less time we have to question our own reality. Then suddenly the children grow up, the mortgage is nearly paid off and we have more time to think about our lives, in particular the meaning of life.
Hence, this is a time we see men in their midlife crisis reliving their youth when they did not live the life they expected as a young man. A consequence of taking on too much responsibility as a young man.
Happiness is a modern fantasy. We can search for it our entire lives but never actually reach the final goal.
Go and have a chat with a therapist and find new meaning to your life