Aside from this nonsensical plot twist, I can't really think of a valid reason to justify him running away, BUT ABOVE ALL, his stubborn silence at this point (a desperate boyfriend who's giving up everything, friends who miss you, a worried foster mother...) I read every (unbearably stretched) chapter with the conviction that "the reason why" will piss me off in the end.
I think the author ran out of ideas around chapter 80 and was racking his brains to stretch the story for another 20/30 chapters. I think that the entirely mental and sentimental ending is boring for a BL manga BUT if, as in this case, it is also poorly done, it takes away value from a product that had defended itself well for 3/4 of the work.











or this story makes no sense?