Friends become harder to make (mostly for men) as you get older and have children. It simply takes more effort and you'll have less time, but having friends that you see regularly is probably more important when you are 40+. It's worth the effort and easier to systemize.
Following up & reaching out can be a big blocker. I just decided that I'm always the one to reach out and I even built myself an Airtable tracker to do this.
Vulnerability is trending up (for lack of a better description). Writing this post was vulnerable and it's #1 on HN. Finding the right way to open up, make it interesting and not seem needy is an very valuable skill.