I feel like I've been through that at least twice in my life. In my early twenties, I quit drinking and I couldn't really relate to my existing friends as then all drank heavily. I needed to make new friends

In my thirties, I went through a crazy breakup and was depressed for a couple of years. I thank the experience changed my personality a lot, but it's hard to explain why. I ended up in a different city (Berlin) and eventually became a different person, more sociable and sporty I think