i can't remember well but this one has a similar plot http://www.mangago.zone/read-manga/koi_no_tsumeato/
Im almost certain that they were students in high school or college and the amnesia wasnt the main plot of the story. It was more about their relationship and trying to date and such and the memory loss was discovered towards the end.
I can remember one of the guys sitting at a cafe or something talking to the owner who was either the other guys family or family friend and they show the guy an old photo of the one who lost their memory and that is how the guy found out about it.
Also, the guy with the memory loss dosnt say anything about it to people, i think.
im looking for a shounen ai or yaoi manga that i read a while ago. It was about a couple of guys who started dating, they where either high school or college aged. One of them had a back story of a rough break up with his ex boyfriend or his boyfriend ran away or disapeared or something, and he was attracted to the other guy coz he reminded him of his ex or something like that. But it turns out that the other guy really was his ex, but had lost his memories.
if i remember right it may have been the accedent that caused his memory lose or whatever caused it was why that had broken up in the past.
But i am not completely sure about the story. For instance there may have been a third person involved, like the two going out now and a friend was the one who dated him in the past or something. So if anyone can name anything that sounds at least vaguely similar i would be great-full(づ ̄ ³ ̄)づ