I'm only 45, and I've noticed for a couple of years I'll have bouts of depression. Not like overwhelming suicidal depression, just seasons of melancholy / moodiness. Strangely enough, I can tell when I'm in it by being argumentative about every meaningless thing, often on here.
You're losing X% of testosterone constantly, science has shown our diets actually cause us men to develop female "estrogen" (especially dairy and foods packaged in plastics), it's a real thing. I'm not drawn to infidelity, or buying stupid expensive toys, that's not how I medicate. Other than being aware of it, and always being communicative about it with my wife, it's never caused any trouble. I don't even know if it's a temporary "midlife crisis", or just normal for all folks. I do think that cleaning up my eating, and rigorous exercise is highly beneficial for me, and again scientifically both of those things help with bodily hormonal balance.