I envy my classmates who date college students...and while my classmate was back home, I had sex with her boyfriend for two days.

Her classmate Yuri has a boyfriend. He's an older university student. I was just jealous of my older boyfriend for some reason. And today is the day to play at his house with Yuri. Naturally, the two got excited and started flirting in front of me. But for some reason, I was jealous of Yuri. What should I do...Even though I'm a friend's boyfriend, I fell in love with him.