Ai to Jouyoku

Sawako Saito's been married for five years, with a kid nowhere in sight. Her mother-in-law pressures her about giving her a grandchild, but her husband constantly turns her down in the bedroom. Sure, he has ED, but can't take it anymore. One day, Hasegawa, the hottest guy at her office, invites her for a little fun behind her husband's back. In her confusion, her mind starts to wander and entertain the thought of an affair with Hasegawa. When she gets home, her husband surprises her with a cake. Turns out she had forgotten it was their fifth wedding anniversary. Ashamed for even slightly being tempted by Hasegawa's invitation, Sawako vows to make things work out with her husband. However, her resolve is short-lived as she discovers some shocking photos on her husband's computer. Why are they mixed in with the couple's photo albums? And more importantly, who exactly did Sawako marry...? (Source: MangaPlaza)