
Well I think they both fell in love in this moment, when they met each other again after 6 years. Since she grew up and everything she def doesn't resemble the dead sister (just how when we grow up we don't look the same as when we were children). Also he never treated her like the other two brothers, it's just the unfortunate situation that they had to meet under those circumstances, and anyways from this point onwards I feel like they are slowly gonna fall in love with each other now that they are more mature!

he probably does even remember her dead sister . back then during kings and queens they married half siblings to keep royal blood line. leaning up to dukes bloodline being half siblings to the king offspring will marry their cousins. i know its gross but its facts. and with particular story line...it's not that much different to other webtoon with royal stuff. this is actually a good one that show a understanding in romance or beginning to.
its disgusting if they any blood relations. but they arent even related. goodness. she is only family cause of adoption if you people forgotten! he is a good ml no lie! and the marriage of ages did not apply in the days like that.