The drama's biggest flaw is that it lacked focus. Weak chemistry between FL and both men. There were some awkward pauses in dialogue and editing. Scenes and transitions were disjointed often. The writing was too loose, especially the infidelity plot which lacked complexity and nuances to be more "human". Sometimes it felt like watching an indie movie written by college students. The drama desperately needed a better build up, the infidelity happened way too early. The same thing can be said about production which often it felt off, although it didn't seem like a "lower" budget drama at first glance. It was really awful how the sound was peaking every time a character shouted.
Go watch "Valid Love (2014)" similar topic but infinitely better.