“If you don’t clean your plate of food, typically rice, then your spouse’s face will have a lot of blemishes.”
My informant was told this belief by her mom. She would tell it to all of her siblings when they were kids. She thinks that her mom just used this to motivate her kids to not be wasteful with their food.
Usually, parents would tell their kids this at the dinner table when they said that they were done eating, but still had food left on their plate.
I think this belief or saying represents the values of not being wasteful, and the importance of marriage in Chinese culture. I’ve also been told a variation of this by my parents, but instead of my spouse’s face having blemishes, she told me that my face would have blemishes, in exactly the pattern of the rice that was left on my plate.