Maybe the usage has shifted (which is kinda why I asked) but stanning comes from the Eminem song Stan. The song is about a fan so crazy obsessive that he ends up killing himself and his girlfriend. So it is, at least originally, not a good thing.
https://mangadex.org/title/c5dcc48a-c7e5-429d-9ddf-c2ba2fd9f158/a-manga-about-a-beautiful-girl this one was cute, the chapters are quite short but from what I've seen on twitter it's been updating regularly.
Thanks for the translation, nice to see this again.
I think he was acting a bit too over the top creepy in this chapter though to be honest. At least try to be normal about it my guy.