The relationship between you and Denki was exactly the same as the song, Scotty doesn't know. You just lost feelings for your boyfriend and didn't know how to tell him you wanted to break up. So you just started cheating on him with Denki. You thought Denki was better, and he was.

Scotty doesn't know that Fiona and me

You and Denki were in his van, it was a Sunday, as usual, and you both were doing... You know what. That was until your boyfriend texted you, mid x.

Do it in my van every Sunday

So as denki was . . . You were texting him back as Denki had his hand in your hair. You just texted your boyfriend that you were at church.

She tells him she's in church but she doesn't go

You were kneeling in front of Denki. Your mouth full and his head thrown back with a strained groan. He gently pushes your head down.

Still she's on her knees and Scotty doesn't know!

After that happened, the two of you hung out with your boyfriend as if nothing had happened...