Every other place, all of my "friends" at work, even those I had outside contact with via Facebook or beers, went radio silent when I moved on.
It's not pessimistic, it's reality. Exceptions that prove the rules, etc.
I understand why people like the office, but it's frustrating to be forced to go into the office just because other people aren't able to have a social life without an office holding their hand through it.
Companies know this, and depend on this effect. It keeps most of their employees "loyal" to the company at an incredibly low cost, since our social instincts are doing most of the work for them.
My best friend is someone I met at work 6+ years ago. I’ve got plenty of other people I stay in touch with. Not all relationships need to be everlasting too. Sometimes work relationships are fun and the authenticity is still real. It’s just that now you’re both not working together, you can’t have the same level of a relationship.
Just because things don’t progress once you’re outside the workplace doesn’t mean it’s not real. Sometimes people have different priorities.
I don't think your experience is representative.