The kind where they secretly take a bunch of pictures of MC and post them in their room... Idk why I just suddenly want to read this. (Please no judging.) Please let me know if you know any. Or if you know which Chinese search terms I should use for raw danmei novels.
The Flowers Blooming Over the Years 年花 by 静水边. Both MC/ML are nearing 40, but it has everything you want. Gong is a stalker and took a bunch of shou's pictures. After printing them, he puts them on the wall. Stalker in Chinese is 跟踪狂.
Dear Pinocchio has a crazy stalker ml but its not obvious in the beginning https://forum.novelupdates.com/threads/dear-pinocchio-bl.89222/
you've probably read it but 'Quickly wear the Face Of the Devil's ML get's pretty stalkery with the whole watching the MC through cameras and taking pics of him all over the place. it's a fun read!
I second Quickly wear the Face Of the Devil, it is a very good story and even if you only want to read the arc where the ML is stalkerish, it's still very good. Of course, reading all the arcs will be the best, so that you get to experience exactly how wonderful the author is.
https://www.novelupdates.com/series/the-perfect-destiny/ is a good one, pretty much the ML is like an insane person that is obssessively inlove with the MC (if that make any sense) ʕ; •`ᴥ•´ʔ