Yeah it breaks me, especially since the boy was the first one to tell him not to forget him to remember him just like he remembered everyone who left for the south, i mean his last words were dont forget me and when the MC turned into a wolf for the first time after being the boy for so long he looks into the water when march and the others are bathing sees his refection of a wolf remembers the boy and turns back into the boy
His first conscious transformation and that moment will never not bring me to tears

I will never get over the fact that we never learnt the name of the boy from the beginning. He was the first humab MC ever met and greatly influenced him, and no matter what when ever i see the MC in that form i get sad (so basically all the time)