I think the increase in depression is due more towards the increasing isolation in our (American) society, and not so much stress. I moved to a new city a few years ago, and between living alone, working remotely, the pandemic causing many things like tech meetups online, and people in the groups I have been involved with not appearing to reciprocate my interest in getting to know them, I've had a lot of times where life has felt pretty meaningless. This is despite a fair amount of internal energy, interest in learning things, etc. (personal growth / fulfillment). My conclusion is that relationships are a fundamental human need.

But we have designed ourselves into isolation. Half of marriages (built-in community) end, most people no longer go to church, there are not really civic organizations any more, etc. I can spend an entire, active Saturday without interacting with anyone: drive to the park in the morning and walk in the woods, go to the art museum (electronic tickets, so not even interaction purchasing a ticket), check books out from the library (self-checkout), buy groceries to cook dinner (self-checkout is usually faster), watch a movie on my home theater setup. That's even without mobile phones, or the numbing false sense of community of social networks.

So not only do we not have the normal human difficulty in actually caring about and loving another person, but we do not even have the social structure to find people to care about. As a result it's easy to live a life where you experience little of enjoying others and being enjoyed by others.