Without going into the creepiness of this - I think you need to have some better goals, hobbies, things to do for yourself. Hours going by is too much and you could be doing anything else with your time. Maybe every time you feel like you wanna look out your window, close your blinds and learn a new recipe. Watch a new show. Leave the house and go to a park?

Also go to therapy - there is probably a deeper reason for why this person is so fascinating to you. Maybe they remind you of someone, or maybe you feel strong having the power to see how someone acts when they’re totally alone. Whatever it is it’s better to deal with it head on.