Sniffing stepmother's underwear was discovered and the ending

Ayaka Tomoda plays a young stepmother living with her husband and teenage son. He was very curious about his stepmother's body, so he spied on her bathing and sniffing her underwear. He really wanted sex with his stepmother. Unfortunately, this was discovered, but in a bad luck, there was a good chance that his mother immediately propositioned him for sex. She said it would help him better understand women's physiology and genitals.