The story is pretty straightforward. Guy gets a cute girlfriend, but she's scared of having sex and wants to wait until they graduate. The mother sees him looking upset about this and he ends up telling her about it. She offers to have sex with him in order to keep their relationship going smoothly, but she ends up falling in love with his cock, as it's better than she's ever had before, including her husband's.
Too far from reality. So very boring. Typical bad work. Botamochi doesn't understand eroticism or Manga. It depicts a slice of daily life, but it depicts something unimaginable. Women don't watch AV and they don't do the same thing.