Helpme

I remember this manhwa ... where this CEO fell in love with a highschool girl in a train. You thought he's was pedo but turns out he was just reminiscing his wife(?). So during their marriage, they went into a rut. The dude was too busy being a ceo to the point he forget his wife' face. I know it was a really sad manhwa and i want to reread it but i forgot it' title.