The person who asks for a different arrangement may be trying to keep resentment from becoming one.

Renegotiating an arrangement is often an act of maintenance. Someone who says they can no longer do the Tuesday collection, or would like the rota altered, is usually acting before the thing curdles into something harder to undo. Left unspoken, the same situation turns into silence, then into distance, then into a version of them you would not recognise.

When someone asks to renegotiate, treat it as care for the relationship rather than a withdrawal from it. Ask what has been hard about the current arrangement. Changing the shape of something early is nearly always cheaper than repairing the feeling that builds when nobody says anything.