These are all! The first book, the last one is about lovers finally getting married.
The second book, if you miss it, it still hurts deeply.
The third book, I would rather be a wife of a poor family than a concubine of a high family.
The fourth book, a different general novel
These are all! Book 1: Because of the persistence of love, it makes people feel distressed and can't help but burst into tears.
Book 2: Love really requires persistence and single-mindedness
Book 3: The last article made me burst into tears
Book 4: In ancient times, cousins could not be together.