Also I don’t think I’d risk being e.g. a teacher - the girls in my high school would casually joke about accusing their teachers of being creeps if they failed a test, etc.
The discrimination pendulum swinged the other way. And as with a lot of discrimination, the criticism is in reality aimed at what you are, not what you do. So you will never get it right in the eyes of those critics. On the other hand the roles of men in society are changing and it's not at all clear "to what". "Be a man but don't really be one, it's complicated".
I mean, I’m lonely and I’m married. Middle age is a tough time for friendships.
Of course there are going to be people telling others to be vulnerable and open, and of course there are also going to be people telling others not to complain because that's dumping their problems on other people.
While the first step should be to join a hobby club or do some volunteer work or find a sport to do (and definitely not the gym or running or any other solo sport). Just find something where you regularly interact with people, and especially the same people over a longer period of time.