After I Agreed to Marry, My Boyfriend's Amnesia Vanished

My boyfriend has a habit of losing his memory, and every time he does, he's convinced my best friend is his girlfriend. Whenever the amnesia hits, he does all the things couples do with her. Holding hands, hugging, kissing... To prove that I'm the one he's actually dating, my phone is always full of kissing photos and chat logs. There are videos too, of people around us confirming that we're the real couple.