Exactly because it’s not that easy and if it was everything would be better
See I get that you relate to this with your own experiences but that girl would be broken forever if she was forced to live apart from her brother. No one forgave him, they just decided to watch over him while he tries to better himself. They said multiple times that the past will not ever be forgotten, but in this case it's best for kanami (?) to have him around (as long as he's actually willing to go to therapy and change, that is, but makoto and the others are keeping an eye on him)
They didn’t forgive him.
i hate the ending as someone who's been abused by a family member why tf did they forgive him that easily I get people can change but the past is still the same. i think they should have lived separately indefinitely or until he's been through considerable therapy.