I Love You, But
It’s hard to explain to children why they have to stop doing something and at the same time validate their feelings. We can say ""I can see you are sad, but it’s time to go sleep.” and that makes it sound like it is negative and can make you feel worse instead. I actually read about a different solution recently and it sounds SO much better, at the same time.
“I know you’re sad that it’s time to go to bed. At the same time, you need to get sleep to be able to play again tomorrow.”