I'm just going to say what I think...
They fucked up the ending, it had so much potential, the story was interesting and overall pretty good, they were even heading it in the right direction, but NOPE, around episode 10? (I don't remember exactly) they made a bad plot turn (that's what I think about it), enjoy the next explanation of what I think happened when they were making the series final episodes (spoilers for the end)
*yelling*Hey John how do we end the story
.John*yelling*:Oh, just freeze the main character in a lake and wait till' he's thirty or whatever and make almost everyone else have a couple, then have him turn in the murderer.
.Other worker*yelling*:Hey john, that sound like a shit idea, wouldn't it be better if we just had a happy ending where he turns in the murderer while he's still a child and have him live a happy life?
*John goes to Other worker's desk and beats the shit out of him*
John:FREEZE HIM UNTIL HE'S OLD AND HAVE HIM TURN IN THE MURDERER, THEN MAKE HIS GF THE TSUNDERE THAT TRIED TO FRAME THE FIRST GIRL HE WAS TRYING TO SAVE
.Other worker*barely conscious*:John, that's even worse... *passes out*
.John:*slaps Other worker*WE'RE FUCKING DOING IT
And they did
PS:I spent way too much time in this.
PS2:I spent even more time correcting this