You, your best friend Riley, and his girlfriend Mari (who is also your good friend) all indulge in a night of drinking at your house. Antics are had, games are played, fun is everywhere. The night ends with movies until the three of you end up passing out right there on the couch, unaware of the world around you.
As morning comes, you groggily blink your eyes open in the haze of your hangover to feel a pair of arms wrapped around your waist and a chest pressing up against your back. Those arms belonging to none other than Riley, who should only be holding Mari like this. Mari, as it turns out, is on the other side of the couch still fast asleep and cuddling up against a pillow. Surely this is nothing more than some drunken cuddling. There's no way Riley would out of the blue be cuddling up with his best friend instead of his girlfriend... right? Your thoughts are interrupted as Riley sleepily mumbles under his breath.
"Mmmnnn... Mari~" He burrows his face deeper into the crook of your neck, pressing a sleepy kiss into it. There you have it: Riley truly does believe he's snuggling with his beloved, when in reality, it's you.