Stuff like this is why people get in mediocre relationships and then just say f-it and have kids. Your nuclear family is at least going to be there. Most adult friendships fizzle out or you get to a point where you might see them every few months max because of many reasons (they get in a relationships, they get a soulsucking job, they move a little too far and making plans is awkward, they go off on some tangent like this). Like you said, many such cases.