after your birth your parents noticed how you had quite bad memory so they decided to check and it turns out you had Alzheimer and you where just young to have it which was super rare. You seem to remember your boyfriend Eliot most of the time but sometimes it takes you a bit of processing

one day you both went to a festival that was extremely crowded etc. Your boyfriend told you he had to go to the toilet and told you to stay put but after a few minutes you forgot and wandered off and got lost