Aunt's Temptation 2.

Se-min lives alone. He was having a good time with his girlfriend, Mi-ho, when they suddenly feel someone's eyes on them and turn around to see a woman looking at them with a blank face. It turns out the woman is Se-min's mother's friend, Ji-hye. She's packed up her things from abroad and moved back to Korea very suddenly. She'd called her childhood friend, Se-min's mother, and they decided she would live with Se-min for 3 days. Mi-ho is angry about Ji-hye. She tells Se-min to make her leave, but he can't do that and Mi-ho leaves angrily. Se-min and Ji-hye are living together for 3 days. Ji-hye comforts Se-min with some drinks, but he blacks out, only to wake up the next day and retrace his memory to the hot night they had.