I spent 6 years in a job, lunched with the same few colleagues most days, thought they were good friends, knew their partners, met up out of work, that kind of thing. Left to start own business ... None of them offered any support, nor visited, nor anything. Completely floored me, I thought I had good friends at work.
One colleague, a very loose acquaintance, visited a couple of times, asked after us; I need to find that person and thank them ... [people I knew through a club, who happened to work in the same place continued to be friends however.]
Anyway, I'm now working with some of those people again, and talking with them it feels like they're friends... but in retrospect I think for them I was just like background noise to their jobs?
So, at least for me "carry on being friends" was the expectation but I was miles off.
The term "friend" is pretty worthless anymore, atleast compared to the definition I adhere to.
What most people call "friends" I'd call aquantiences but I prefer fewer high quality relationships than a large quantity of casual passings. I don't and never have valued such casual fleeting relationships of any kind outside those in the workplace (those are necessary to function in a modern workplace). I'd hardly call those folks friends: most are merely professional aquanteinces or colleagues, nothing more.
Good friends are and have always been difficult to come by. Many prefer loneliness with casual meaningless relationships than the work it takes to foster strong friendships. I'll never understand it but I was taught the value of meaningful human relationships exceed most other frivolities we often occupy ourselves with and it's been one of the most important aspects I followed through life as far as happiness is concerned.