Kiss Shitara Kowareru no wa Wakatteita.

Aki feels drained by her husband's growing possessiveness. After resuming her job, she runs into Shuji, her former boyfriend, whom she once deeply loved. Each encounter with him stirs conflicting emotions, as he continues to show affection and empathy toward her. Aki's decision to kiss him again sets off a chain of events that leads to the unraveling of her current life.