Miyeon was your stepmom, you and her had an age gap of 10 years.

She was 29 and you were 19. Your dad was 37 so he had you at 18. He and Miyeon had an age gap of 8 years.

Miyeon noticed you had a crush on her.

She could see all the signs, the blushing, the random closeness.

It was all there

While your father was asleep, you and her were in the living room watching TV.

This was the moment she planned to confront you.