Recommendations

Fake sibling/family relationship
FL gets jealous sometimes
Smart ML
ML with issues
First love
lives in same house

Two best friends (one of them being a university professor) investigate and solve supernatural happenings

Both dramas follow the female lead and her crush through high school, college, and adulthood. Both dramas also show the male lead go abroad for education and return to China as successful adults.

Extraordinary You and Love Crossed similarities
~Romance, Youth, Drama, Friendship, FANTASY
~Rich male lead, Character Development, Amnesia, Naive Female lead, Happy
Ending, Smart male lead, Female leads have lost their mothers, Misunderstanding,
Virtual reality

Both modern C-dramas feature a mature, mutually supportive and heartwarming relationship between the leads. They face potential misunderstandings and relationship challenges by trusting one another, rather than with tropey fights and breakups. The genres are somewhat different (Love o2o has more light silliness interspersed with the romance while Forever is more sedate and focused) but both will have you smiling throughout.

topic: babies raised by others. In this drama the ML receives her 5 years old daughter. He didn't know about her existence. The mother left her to be raised by him. He's a famous actor and he doesn't care about his daughter. He pays a caretaker to raise her and they fall in love.

I add this drama because of the topic of babies raised by others that maybe family or not. In My Lucky Star, the FL was raised by his uncle because her parents died.
His ex-boyfriend betrayed her: he got married and his wife gave birth to a baby girl. The wife died and the ex-boyfriend became a widower. The baby needed a heart transplant and he committed a crime to get money. He went to jail and the FL decides to raises her as her daughter.

Both have humans who turn into monsters.
The world facing a huge human crisis.

You Yi and Yan Wei dynamic just reminds me of Dao and Koi though two dramas set in different times. These are the same since Dao is also a writer and Koi also protects Dao.

Childhood friendship, misunderstanding, meet again years later and love prevails! Love is Sweet is way better though

Both
- lost their mother early
- kids had to fend for themselves (although Go Ahead adults were much nicer & heartwarming)
- had the elder brother figure that took care of the younger siblings

Both are historical dramas where the male lead is a monster of sorts, a female lead that sometimes dresses men's clothes, plus the female lead's father sort of paranoid sometimes. Drama plots are not exactly the same but the similarities above plus the way the female leads addresses the male lead as seonbinim (scholar) kinda made me remind the dramas of each other.

Both female leads have problems with communicating. In Orange Days, FL is Deaf while Komi-san has poor communication skills. Another similarity is how both male leads helped FL have more friends. But keep in mind that Orange Days is a dramatic show while Komi-san is more of comedy. Anyways, both lead actresses had to act only with gestures, which could be a difficult task.

It has similar vibes. I love wlw representation. Both are wholesome, short and sweet. I love the actors in both. They have so much chemistry.

Similar vibes. I feel like both of these are very realistic in my queer experiences. In both of them a boy gets between the wlw relationship and ruins it. I feel that they both have ambiguous endings.