What does it mean that a gentleman is affectionate and stops at ceremony?

Hello, "A gentleman's affection stops at ceremony". This sentence comes from The Book of Songs. It is said that Guan Ju, the first poem of The Book of Songs edited by Confucius, describes a young man who can't sleep because he yearns for a woman. Zi Xia Zuo, a student of Confucius, said, "Being affectionate stops at propriety", which is what Confucius advocated.

"A gentleman's affection stops at ceremony" means that a gentleman, like ordinary people, has a worldly desires, and his sense of affection is ok, but it must conform to the etiquette and cannot exceed the boundaries of etiquette. Nowadays, it is mostly used in love, that is, when you have an affection for a person, you can still be polite and not impulsive, not like a pervert bandit.