Babysitter

In both, there is a woman, apparently a nice person, who wants to take another woman's husband and she has a hidden intention.

It may not be similar plot line, but both dramas were made by director Kim Yong Soo, which means beautiful, artistic scenes and incredible soundtrack. Both really worth watching. :)

Jo Yeo Jung stars in both and she's wild. Her characters start in a similar places, as a seemingly too good to be true housewifes having perfect lives. Both shows tackle infidelity. Both have one character approaching others with a hidden agenda and one that's an incorrigible cheater falling lower and lower, too.