Some work friendships end the day someone quits. The ones that don’t were real the whole time.

Most of what happens at a job is produced by the job. You are thrown together for twenty hours a week, you have the same complaints, and that generates something that feels like friendship and is largely circumstantial. The test arrives when the shared shifts stop, because then somebody has to make an effort that nothing is prompting, and only a few of them survive that.

Do not be insulted when one does not. It was a good arrangement and it ran its course. For the one or two you actually want, send the first message after you leave rather than waiting, since that is the whole difference.