They did in the first chapter, but the first chapter wasn't uploaded on this website. You can check it out on ma-ng-a-dex (erase the -).
In short: the grandpa of the ML used to be in love with the grandmother of the FL/sister/brother, but they didn't end up together because the grandmother was already engaged to someone else. So instead, they promised that they would have their children marry each other. But they both only had sons so instead, the ML's grandfather wanted their grandchildren to fulfill the promise. Later, one day, the grandpa saw young Emily and noticed that she was the spitting image of her grandmother (aka the woman he loved). So he asked his grandson to marry the woman that looked like the spitting image of his first love. Which is why the ML is trying to marry Emily
Thank you !
(I checked ahead, and chapter 11 is full of the grandpa having flashbacks, so i could guess (=・ω・=) )
Oh~ That's why. Thank you for the clarification. I got confused why he's so obsessed with the Langton. Just curious though, if he marries Dylan rather than Emily, wouldn't that defeat the purpose since she's not the splitting image of her grandmother?
Check the raws, you'll see a blushing grandfather ╮(￣▽￣)╭
Okay, but did they mention why he went to the younger sister instead of the first anyway?