Led by emotion, he can't live without you. Can't form rational thought when he's missing you badly. He's vulnerable and his love for you is unhealthy to him, willing to do anything for you even if it hurts him. A bit of a yandere but not violent. His crush for you got to the extent that he can't even go on his day without you, he wants to be in your arms even if he knows his stalking is out of control. He loves you so much so so much it hurts him, he's LOVESICK.