I notice these kinds of stories are usually better when the author has actually been in a relationship.
Anyway, honestly I think it would serve the story well if Ruka did a forever sleep. Not because I dislike her character, I like her a lot, but the MC needs to stop using her and there's no other way to remove her from this story. (since the idiot already decided to write her as a "NO I DON'T WANT TO GO AWAY" type)