The ending I'm seeing is Yuu getting back with Yami, partly because he's worried to leave her alone and partly because he will think that the only love he could ever get is from Yami, now that Hikari rejected him. He then lives short and miserable life with Yami, getting killed in marital...
Was he harsh? He just insisted that if his studies are affected that much from taking care of his siblings, they should hire a nanny so he has less burden on him. His grades did drop significantly in only a year, he could actually fail if this continues.