Both are Republican Era mini dramas in which the FL and detective ML are working together to solve murders and mysteries around the city.

Both are Republican Era dramas about mysteries that initially appear to be supernatural.
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Both are about a rich ML and poor FL who are planning to get married only to be driven apart due to scheming by the ML's mother/se=mother. Five years later, the couple crosses paths again, and the ML discovers the FL has a daughter who he instantly realizes is his. Both children are cute and precocious, befriending the ML even more he realizes they're the FL's child.

Both are about a rich ML and poor FL who plan to get married, only to be driven apart by misunderstandings and the ML's relatives. Five years later, the ML, still angry and blaming the FL, crosses paths with her again and discovers she'd given birth to and has been raising their daughter.

Both are about a couple who break up due to misunderstandings. Five years later the two, still angry at each other, cross paths again, and the ML discovers he has a child he didn't know existed who the FL has been raising alone.

Both are about a couple who break up while the FL is pregnant with their daughter, only to reunite five years later. The ML instantly suspects that the child is his and gets a DNA test to try to confirm it. There's a SFL chasing the ML who becomes involved as well. Both MLs are wealthy.

Both are a gender-flipped version of each other - the FL vs. ML believes their baby died, causing the couple to break up. The other parent (father vs. mother) raises the child alone and five years later they cross paths again, with the other parent suspecting and trying to confirm if the child is their's.

Both are dramas in which the ML treats the FL coldly, blaming her for something she didn't do, and the two separate, with the FL giving birth to and raising their child alone. Both have rich ML/poor FL, a SML pursuing the FL, and scheming relatives of the ML.

Both couples break up due to the ML's family's manipulations and misunderstandings, with the ML believing the FL had a miscarriage. Five years later, the couple meets again, with the ML discovering the baby lived and he has a child.

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Both are historical dramas in which the ML is ill with a short time left to live that he then shortens saving the FL. They are weak physically but strong mentally and in both dramas are involved in the power struggle for the throne. Both MLs are doctors or work as doctors for a time. Both FLs misunderstand and are separated from the ML for a long time.