I Have a Date with the Demon Lord

When the cute and clever little fairy met the sinister and gentle Demon Lord, "Did anything happen in this room last night?" "Yes." "Yes?" "Of course things can only happen in the room."... "You haven't told me your name yet." "Still lonely." "The autumn colors are still there, are you still lonely again?"... When the facts were revealed one by one, "Have you gone to the library?" "..." "Why not?" "..." "Yue'er, you have never believed me..."... "I shouldn't have existed in the world, maybe I asked for too much." "Then if I give me to you, you should live well, forever and ever!"... When the memory returns to the first meeting and reincarnation reunites, "I miss you so much." "But I don't." "You..." "I'm just always by your side. Don't think about it, I always have you."