Responses
He told him to give her time. Basically a 'you're too young; let's see what the future brings', so 1) who knows if he'll still be in live with her in 13+ years, and 2) if it were to actually go that way A) they are not related by blood and B) he fell in love with her before step-brother was a title he could claim.
Did the ML tell his son to marry his step sister when he grows up?!??!?? Idk I was just skimming but wth