《幻之光Maborosi》ending scene

i just ...... I just don't understand ... why he killed himself... Why he was walking along the tracks... Once i start thinking about it i can't stop Why... do you think he did it? He said the sea calls you Dad used to go out to sea He says when he was out alone, he used to see a beautiful light, shimmering in the distance, calling him I think it can happen to anyone