Fall in Love With Me (2014)

The main character has a split personality which happens in both show. Also, the main guy is both oozing out with charisma.

There's not much similarity but I got reminded of Fall in Love with Me when I was watching The Brightest Star in the Sky. Many songs of the soundtrack is also sung by the male lead which are pretty good.
- Both of the male leads are rich with the female leads struggling with money (sorta)

Both follow a similar premise of a successful businessman disguising himself as someone innocuous to get close to the female lead. Once this deception is revealed, he has to rebuild the trust he lost.

Another Taiwanese drama with a haters-turned-lovers central romance. Also, there's some similar professional intrigue (including a hostile takeover) but it's at a travel agency instead of an ad agency.

They both are rich and famous Male Leads, they both disguise themselves to be with the Female Lead, They both use different names to keep their identity hidden. both male leads are attractive, both female leads are also attractive.

They are both Taiwanese and they have the same guy acting as the male lead in both of them he plays the part of a rich and arrogant guy.

Both dramas feature a storyline where a male protagonist assumes a different identity to hide his true identity from the public. The dramas also explore themes of love, mistaken identity, and the challenges faced by celebrities.

The male lead hides his true identity in both series. Hi My Sweetheart has a revenge theme. The male lead in Fall in Love With Me wants to help the small company of the female lead succeed.

Both of these dramas depict a male lead with two distinct and contrasting personas as well as a feisty female lead who grows fond of the male lead's gentler side. These dramas share similar tropes, yet are different due to their execution and plot devices (for example, SHNPT has a supernatural element).

Its similar in the main lead changing into two character with totally opposite personalities. The secret life of my secretary where the female lead accidentally change her character to another person without the male lead knowing. While, Fall in love with me, the male lead changes his personality into complete opposite of himself without being recognize by the female lead