You can't abandon your sister for ten years and then act like you have any right "be by her side". The mom too is probably going to have some excuse for abandoning her.
Aria is based. So many harem mangas have the wife/fiancé make a harem without asking the mc if he even wants a harem in the first place and no one ever questions it.x
Am I mis-remembering something or is the author just forgetting that he made Zenjirou sign an agreement with the twin kingdoms saying that wouldn't take a wife from there because one of his ancestors was from the twin kingdoms and they didn't want to strengthen that bloodline any further?