What is the original occurrence of this specific memory-loss / amnesia plot?

I am not searching for a specific movie I have seen, hence the question may be vague or a little off-topic (hopefully not too far). I am searching for the original movie (or source, maybe even in literature) that the following plot line originated from:

Person A and Person B had a romantic relationship (boyfriend/girlfriend, married, or any form of love interest). Person B has an accident which results in memory loss / amnesia and does not remember anything specific about the relationship, hence starts a new life or relationship with person C. Person B is considered missing and searched for by person A, or person B stumbles upon person A. Person A discovers what has happened, however leaves it that way (possibly to personal grief) since person B is happy (or happier) this way.

Person B is likely to be female, person A is likely to be male. Person C does not have to exist, and if he does, person A may or may not confront him. Person A may find out about the accident from person B or person C. Person B may or may not be faking amnesia, and if not, the memories may or may not return. Also, person A may or may not decide to confront person B, in case he/she does, he may or may not tell person B about his/her past.

I know the current description allows for plenty of variation, but I think this kind of plot pattern is very recognizable and memorable. Innale, a Malayalam film from 1990, uses this plot line, though I doubt it originated from there. I have also seen it used elsewhere, but so far the aforementioned movie is the oldest source I know of.

Any ideas for the original source?