I resonated with this well. I think this happened not only when people in EU or USA moved from one place to another. My country, Singapore, is a small city. Despite moving from a place to another, as we grow up, our circle of friends shrink a lot - commonly because of marriage.

A lot of friends who got married gradually became out of contact. They are inclined by the hours towards their family, raising kids and being drawn within the box of "in-laws" life. Pretty challenging for the woman to go out freely, weekly, to gather with friends, especially without bringing children along.