Lots of reasons, reasons that have built up over the time he's been here, he screws up, drowns his issues in booze or when he gives that up, painkillers, he guilt trips about what isn't his fault and ignores the fact he sold his damn soul so that Bela Freaking Talbot could stay out of the pit. He makes you upset, he makes you worried, and you want to fix him. I know he's your friend but you could have better ones.