That's what I thought at first too! But then I realized it was the same video as before and Sawamura just wasn't paying attention after they had sex. So, the person Miyuki was having sex with was Sawamura (=・ω・=)
It's the same video, which is why Sawamura cut it to just the end, where Miyuki had grabbed the phone.
Oh! Thank goodness I was hoping that it wasn't cheating or anything I'm glad it turned out that way.
I completely agree! I had to stare at the page for a couple minutes before I figured it out!
Was he having sex with someone else? Is that not cheating right there?.... well whatever...I'll see it to the end.