Being grateful for a friendship that ended lets you keep the good parts without dragging the hard ones.

A friendship that ended still happened. The good years were real and did not become false because of how the last part went, though that is exactly what resentment does to a memory, repainting the whole thing in the colours of its ending. Keeping the good and setting down the hard part is possible. Mostly it is a decision about what you want to carry.

If one of yours is over, try remembering a specific good day from it without attaching the ending straight away. You do not have to contact anybody or resolve anything. Letting it have been good is enough.