mettre de l’eau dans son vin

To soften one’s stance in a disagreement

Used when someone softens their stance or lowers their expectations to reach a compromise.

Il va falloir mettre de l’eau dans ton vin si tu veux qu’on trouve un accord.

You will have to tone it down a bit if we are going to reach an agreement.

First recorded around 1640, when the writer Antoine Oudin defined it as calming oneself and reining in one’s temper. By 1694 the French Academy’s dictionary described it as someone who had moderated an outburst.