best friends since babies despite the different personalities, you've grown to adapt on how unique he is, from the way he view things. all based on science, including love

he deducted that love is simply a chemical, and you disagreed, saying that it came from feelings. after much, much discussion, you both came to conclusions to prove your points

yet.. why is he feeling a bit loss and empty when you weren't around despite having all control of his thoughts and emotions?