I mean stalking n general is creepy I would say if you make attempts to form a actual relationship with the person your stalking and your no longer stalking and you tell the person then they decide if it’s cool and than you can move past it in this story it was really only taking pictures and the whole sleep stuff at least he didn’t r@pe the sensei but the sensei forgave him so idk
Some people has weird festishes collecting their stuff is equal to feeling you have them within you and can see or touch them through their stuff anytime ,as well taking pictures is also harmful stalking in general in today's world is actually scary af anyone can harm you in the case of this yaoi manga sensei is chill cuz he is younger than him and his former student for him it's like he likes him so much which is weird to think as grown up person also both of them are men in general sense for uke it doesn't seem that much harmful.
Is it ok to stalk someone if the other person is chill about it and it's harmless stalking like taking pics and keep it for us eyes only and collecting stuff the other person threw away? What's the point of going through the trouble of doing all that anyway?