"If possible I would like someone alive."
It was a lie he told her and himself, but his actions betrayed those words by rejecting that girl who confessed. His feelings for Kouko clearly overpowers his preference for a living girl.
I kind of feel sorry for the other girl, but I also commend his dedication to loving her. Had this oneshot gone on any longer, the usual development would be: making her happy would have allowed her to pass on in peace. Then he's alone.