MC is very insecure (insecurities isn't abt relationship)

Very insecure abt their looks, etc. (I've watched Gangnam beauty)

Prefer if it's romance, but as long as the story is good then it's ok

'insecurities  isn't abt relationship' meaning the focus of MC insecurities isn't abt their partner (accuse of cheating, extreme jealousy blegh, etc) 

• +1 My Secret Romance - FL is extremely insecure about being perceived as "easy", mainly because her mother was an adult film actress
• The Happy Loner - FL is extremely insecure about emotional vulnerability and completely avoids all emotional intimacy / any situation that might lead to becoming emotionally reliant on another person.
• Wednesday 3:30 PM - The FL's boyfriend breaks up with her and starts dating their mutual coworker. She's convinced it was because she looked particularly worn down in the middle of the work week and becomes insecure about whether her appearance is youthful and energetic vs. old and worn out. In lieu of rent, the ML "pays" the FL by taking her out on fake dates in the middle of the week so she can post selfies where she looks happy and energized. 
• She Was Pretty - When the ML and FL knew each other as kids, the FL was considered pretty and the ML was considered overweight. The ML moves abroad, and when he returns as an adult he is very in shape and good looking, while the FL's looks are considered plain / unattractive. Due to her insecurities, the FL sends her good-looking friend in her place when the ML asks to meet up again.
• Another Miss Oh - The FL shares a name with an attractive and popular classmate (who ends up working at the same company and having more success later in life). She (understandably) develops a bit of a complex about it.
• +1 The K2 - The FL is the illegitimate daughter of a presidential candidate. Her father has always hidden her away, essentially under various forms of house arrest, and she had a traumatic experience with the press as a child which end up making her very shy / reclusive.
• Ugly Duckling Series: Perfect Match - The FL has plastic surgery and due to an allergic reaction to the chemicals involved she develops serious, long-term acne. She decides to hideout / study in the countryside until her skin recovers.
• Where Stars Land - The ML is really insecure about his bionic arm, and about his disability. Confusingly insecure.