Unfriending Etiquette

I have two neighbours who used to be forum regulars that haven't played since the Valentine's update. I can't bring myself to delete them.

When it comes to neigbours I added randomly, I don't hesitate to delete them if they haven't played in a few days and I get requests from other players (especially forum regulars). Maybe they are on holidays, but they'll find new neighbours easily once they're back.