Instead of handwaving* it.
I completely agree, I feel like they needed to resolve their issues face to face, and not in such a half-baked way
I used to be surprised by the stereotype of sibling-fighting because I have 8 siblings and we never fought like that.
I guess we're the abnormal ones though
I don't think so. My sister and I are extremely close and always have been. We've bickered of course, but there was never a time when my sister would have said anything even remotely close to what the character's brother did. Both of my parents worked, so my older sister basically raised me growing up. She's always come to my defense against others, even other members of our family.
I like the story's pace, but... I don't like how they deal with the brother. I understand where he's coming from. I personally don't have siblings, but I grew alongside my cousins who constantly fought. The older sister would normally make a biting remark, and the younger brother, crying, would try to retaliate with fists only to be held back.
When I was younger I thought that kind of relationship was unhealthy. Even now, I do, and I think the sister's actions have a lot to do with how the brother turned to shyness and introversion . However, when I see them now, they clearly have so much respect for each other. And despite their rocky past, they love each other, and the sister's already an adult who finds time to dote on her brother despite being busy with pharmaceutical studies.
So yes, I understand the older brother's frustrations in this story, and why he would lash out. But at the same time, I don't like how the manga portrays him as an unfortunate victim of the consequences, when he did some harsh things. His feelings should not justify his actions. The manga should make it clear that what he did was wrong, instead of handwriting it through the friend's explanation.