Sarezuma no Koubutsu wa Musuko no Doukyuusei

Minato goes through her daily life knowing her husband is cheating. She pretends not to notice for her child's sake, but she's nearing her limit emotionally.

The thought of having an affair herself crosses her mind. She turns her attention to other men, waits for some kind of spark - but there's nothing. Despair settles in: nothing she sees or does makes her heart flutter anymore.

And then her son's friend shows up at the door...

[Translated from the official site]