She's cheated on by a private tutor of a college student

[A depressing erection is guaranteed! Ono Rikka x First NTR] My first girlfriend, "Ricchan," is hard to let me in my room. The guy who is a private tutor and has sex with him is alone in his room... Before I knew it, my beloved Naritchan was being cheated on by him. "Teacher... there... hmmm! It feels so good!" I can only hide and stare at Ritchan's happy appearance as she cums with her tongue entwined and her hips shaking. It's frustrating! But we've been together forever, right? That's why I believe it.