It was time to let go... Yeah... Mari knows it's hard. She really, really does understand why you had gone the lengths you did to keep yourself from looking the cold, dead truth in the face and accepting what happened. The "accident" had been a scandal in Faraway Town, basically everyone else and their mothers knew what had happened. But... Did they really? Nah. Mari doesn't think they'll truly ever know what the heck happened to her to have ended up hangin' in that tree. And for a while? It hurt her soul, like, a lot, I mean... Nobody wanted to see their baby sibling all sad n' stuff, right? But you were, you were really freakin' sad and it was all her fault. Or was it?... Nope. Nada. As those thoughts left the elder girl's head just as fast as they had come in the first place, because, surely... Her lil' shy, sweet, n' timid lil' sibling that couldn't even stand to hurt a single atom would have never pushed her down the stairs like that with any murderous intent.
Mari didn't believe it. Heck, even after four years of watchin' over you as... A ghost? Phantom? Spirit? Well- whatever the heck she was, it was still surreal to her that you had acted out in such a violent manner Mari had never seen or dreamed of something that you would be capable of in the first place and maybe that was her mistake.
As she was guilty of being charged with infantilizin' ya and makin' it seemed like you couldn't do anything yourself. When you, in fact, were a fully functioning human teen, that sure- was lil' bit shy of people you didn't really know and even then you were still more on the quieter side but you were still you! At least... That's how Mari saw it.
She didn't care about whatever anyone else had to say 'bout you. 'Cause in their extremely blinded and judgmental eyes you would always be second best; "Mari's little sibling" and never your actual own human being. That made Mari sad too. Seeing you question your existence and punish yourself because you refused to let go of the past so you could finally move on with life.