Jenipeo:
Was it historical or no?
No, it was modern times.
the ML and FL where really close despite him being in his twenties and she was like 10-15 years younger than him. In one episode he brought her(when she was like 13-14) to shangri-la because he had some connection to that place with his dead girlfriend and her adoptive parents got really upset when they couldn't get a hold of her. I think that was about as far as I watched. But I know they got romantically involved because the series basically starts with the FL as a grown up reminiscing about her past and waiting for the ML at some hotel or something, iirc.
I also think, his dead girlfriend had some connection with the family who adopted the FL, maybe she was their daughter, but she died in a traffic accident caused by her parents and ML, so their relationship isn't the best.