How?
you need to choose every intimate option with Mal0, tell Sung about Mal0, dont restrict Mal0, accept Sung's offer to relive you, then after caging Mal0 release them from the cage, block forgot her names access to the cage, then when Sung leaves you go to what's her name for advice, accept her offer, tell her you've been intimate with Mal0 and you'll get the last scene