Fear of missing out (FOMO) is sometimes also called social panic.
It is a persistent anxiety rooted in the worry that you’re missing something. People who experience it feel that something especially meaningful is happening to others while they’re away. This form of social anxiety has been described as a desire to stay continuously connected to what other people are doing. It has also been defined as a fear of regret that makes it hard to stop worrying about missed chances to make social connections, have new experiences, invest, or enjoy other good things.
In other words, when you imagine how things could have gone differently, the anxiety keeps coming back, making every decision about how to spend your time feel like the wrong one.