Batsukoi

The story follows Mirumachi Kahori, a lawyer who repeatedly finds herself in disastrous relationships and ends up facing unexpected challenges. Though Kahori enjoys savoring the fun parts of romance while sticking to her “no cheating” rule, she unintentionally gets involved in an affair with Sunagoya, a high school teacher, unaware that he’s in the midst of divorce negotiations.
(Source: Drama-Otaku)
~~ Adapted from the manga series "Batsukoi" (バツコイ) by Tsukiko (月子).