I hope your love comes from the heart, not from the ups and downs in the world. What does this mean?

Don't forget your true heart at any time, don't indulge in this floating world, don't go with the flow, and always keep a "pure heart".

Going with the flow means going with the flow and being happy with it. From Epitaph of Magistrate Jun in Right Classroom.

Idioms are stereotypes in Chinese vocabulary. Idioms, everyone says they have become words, and so do idioms. Idioms are mostly four-character, and some are three-character, five-character or even more than seven-character. Idiom is a major feature of traditional culture in China, which has a fixed structure and a fixed sentence, indicating a certain meaning. It is applied to a sentence as a whole, with subject, object, attribute and other components. A large part of idioms are passed down from ancient times and represent a story or allusion. Some idioms are just a miniature sentence. Idiom is a ready-made word, similar to idioms and proverbs, but slightly different.