She knew what he was going through but still placed her doubts on him. She knew everything what he was doing for her family, her sister but expects that he should just give her all the time and also wants that he do his best for her family too. I don't know what she wanted from him but for that she had to speak her thoughts but instead chose to remain silent. You can't blame the other party if you are not placing your thoughts on the table and not conversing your problems. I don't know what everyone thinks but not every person has some hidden powers/talent that can read the mood of their partner without any conversation and solve their problems.
This manhwa is very realistic in the way it depicts the reality that there is nothing like happy relationship all the time, there will always be skirmishes, misunderstandings and will not always lead to the so called happy ending. You all (maybe) will find this post annoying as I'm dissing the FL but it's true that she behaves like a grumpy child on one hand she does everything for her family but doesn't have the courage to bear the consequences, she always had the conflicting thoughts in her mind and thought everything she was doing was good. The ML was also at fault I admit that but the way everyone treats the ML as a trash and the FL as some damsel in distress (as she has been through depression), these kind of bias is very annoying to see.