This basically shows how immature Haru was at the age of 17 and how mature Ren is at the same age. Both have been through a lot of Pain but one of them clearly is a whiny rat.
Immature? Maybe. But remember in that time frame haru spent the summer taking care of an unsociable child & brought him out of his shell. At that age he survived an accident, coma & rehab basically by himself (mikiko was only there for the finances thru haruka...the only decent thing that witch ever did for her son). At that age he quit school to get a job to support himself and help with the twins finances. Nobody could bother picking him up and taking him home after being hospitolized for almost 5mths? I think he did pretty well for an immature person.
Guys remember that after the accident he completely forgot about his summer in Canada so he forgot about Ren! Also after he went to the rehab place he was there only 5 months because he has a fling with a nurse there and he was asked to leave, then he drop out of high school and completely drop out of his own life or the lives of his family( the twins)That's what Shima had said in one of the early chapter, then Haru had a few jobs, then the whole Host thing to help with the twins! So yeah Haru had it a bit ruff but not as ruff as Ren did. Also understand the Haru is the adult who has had an ok life in the since that everyone saids that he is lucky cause he has always been loved and Ren is the teenager who is really smart but has few not none in social skills so it's a bit hard for him to socialize. But still I just love this manga and can't wait for the next update! Thou I'll have it wait but that's ok!
Maybe it's not a perfect ending... A story where all the problems aren't solved or even addressed, there was something else sensei wanted to focus on. Grieving people do strange things. They're happy but the thoughts still linger. Maybe this isn't the story that everyone wants to hear but this is the story that sensei wanted to tell, and she has achieved that.