Recommendations

-it’s both contact marriage
-once of the main character have a memory that’s deep it mind
-both of the Chinese drama main character all know each other when they’re little
-both got in contact for a year
-fell in love gradually
-all got the memory at his/her birthday
There’s a lot more can’t list them all sorry.

Both of these dramas focus on the lives of people involved in selling others or themselves in the sex trade and how they are slowly destroyed by the brutality of the business.

Chinese paladin 4 similar to Chinese paladin fantasy mirror because I think it is spin off to fourth installment

A journey of miserable man curing his own injuries with the help of FL and finding new love at the same time.

A journey of miserable man curing his own injuries with the help of females in his life and finding new love at the same time.

Both have issues related to young gay men discovering their sexualities. Both deals with LGBTQ lives and struggles.
Both series are the best representation of a new BL (Boys love) trend: more reality to address LGBTQ agendas.

The similarity lies in the
Very simple cute leads
working busy male lead
The love after marriage genre

To put it simply the similarity is in

the love after marriage genre

The similarities:
1.Cute female lead
2.Contract /arranged marriage
3.Love after marriage

The similarities:
Simple ,beautiful and bright female lead

Quick marriage contract/arranged

Love after marriage

Although the setting is in no way similar because K2 is all about action and fighting scenes, the part about the male lead taking care of the female lead is the same. In Liar Game, the male lead takes care of the too-kind and naive girl through the entire drama. And even though there is not romance, there are little hints about a relationship between the MCs.

Childhood friends as a romance plot are great, but trying to be first in your craft and your biggest rival are your best friend(s)... that's it

FL are cheerful
There is also Teacher and student relationship but its more likely Senior and Junior relationship.
ML is the leader of Sect Tai Chi. And hes so strong. He helped FL to be more powerful.
There is another story with the grandparents in the past too.

Sad...

Tearjerkers.