Cities don't necessarily fix all this. I lived the first 21 years of my live in the boonies. Like the real boonies. I hated the isolation the last like 6 years. I moved to montreal finally (well the suburbs for a few years first). I did have a fairly active social life for some years. But now it was ten years in mtl last december and I'm still as isolated as i was . Why? Because turns out places didn't make me lonely, my social anxiety problems and my personality and low tolerance of others makes me lonely and isolated.
Its not always where you are but sometimes who you are. As a teen I used to dream my life would be amazing an exciting in a city. I was very wrong.