MC in his canon timeline isn't marry, but wonder what about FMC, with her personality worse, come to worse she might end up marrying some old dude who died way before her and she kills herself in her early 40s something, hey maybe that is when MC suddenly got send back in time.
@gamekram
The problem is MC, trying to hide he came from the future, if he knows something like that people will get suspicious. Some scientists might decide to study him to learn the concept of soul or other stuff. Also, personally I think this is a different world, so some tragic event might not take places