It's not unfair at all. Because Moriya stood no chance to begin with, whether Takae reincarnated or not. The only reason Keisuke survived his wife's death was Mai, and had Takae not reincarnated Moriya would have gotten the same rejection. He had completely given up on life except for Mai, and it's ridiculous on her end to blame the reincarnation. In fact the only reason she even had this shot to confess at all is because Takae reincarnated and Keisuke stopped being heartbroken.