Perhaps "remember when you met with your friends?"
But taking a photo (possibly a group photo) is a more natural way to do that. Maybe it should integrate with photo-taking somehow?
It would be annoying if you met up, forgot to do the ritual in person, and had no way to fix it.
I don't really like the idea of an app telling me how to manage my friendships, my view is that people can handle their relationships without intervention. I'm not sure what problem it is trying to solve.
While this probably could only be done with the cooperation of Apple/Google, something like what they did for contact tracing during the pandemic would be ideal. Picking up that you were in the proximity of various friends without any active effort.
https://covid19.apple.com/contacttracing