obsessively shadowing
You can't stop watching someone you're completely smitten with because you see them every day and you're too lazy to do anything else. They probably don't even know you exist and don't care.
I've been watching her in math class for three months. She still doesn't know I exist.
He sits right behind me in lunch. I know what he eats every day. He doesn't know my name.
I follow her to the bathroom. I don't know why. I just do it.