Modern breakup fic
Arthur breaks up with Merlin after seeing him in a sex tape cheating on him. However Merlin has been framed, I think by Mordred? who wants Arthur for himself. Mordred magically manipulates the tape to make it look like Merlin was cheating. Eventually Merlin is exonerated and happy ending. Sorry can't remember any other details. Maybe Uther was behind it, not sure. Driving me crazy, help please!