Well , in his own way he does "love" our mc . Following the definition of love ( feel deep affection or sexual love for (someone). ) , he does feel sexually attracted but has missed an important part , affection . That may be because he is psychologically damaged , but still , I don't think we should expand the criteria in definition . But rather than love , I'd personally call it an obsessive attachment , that's different. In love , you'd probably respect the wishes of your loved one and care for them (the affection part) , which he constantly couldn't. So by definition , he can't love our mc ( he's too mentally ill / damaged for that ) , but just like we hold onto our old possessions (due to memories,etc) , he held onto Kyung Soo .
Just like we may abuse our plushies , soft toys , etc but still be attached (during childhood) , he felt attached to Kyung Soo . So yes , he "loved" Kyung Soo , but in a de-humanising way .
So the question here is " does yule love kyungsoo?"