to dwell on, to brood over, to keep going over
Je pense que tu as tort de ressasser ces rêves.
I think you're wrong to keep dwelling on these dreams.
— Harry Potter et la Coupe de feu (2005)
Si je ne l'avais pas retrouvé, j'aurais passé la journée à ressasser.
If I hadn’t found it again, I would have spent the day dwelling on it.
— Aquarius (2016)