A Sunday that used to go wrong
An illustration, not a real couple.
The dishes are done. One of you says, "Can we talk about the weekend plans?" and twenty minutes later you're arguing about something from March. Nobody planned it. It was the only time either of you raised anything, so everything came at once.
A weekly check-in moves those topics to a set time with a small, fixed shape. One topic gets the floor. The rest waits for next week, and both of you know it will get its turn.
A check-in works because the hard topic gets a time, not because the questions are clever.