Plot wise, it works because Chika is tolerant and doesn't really hate what Yamada is doing. That's why it's important to note that Chika had the chance to fight against Yamada but chose to tolerate his stalking. Chika ACCEPTED Yamada. If there was no consent, then I'll talk shit about this. But these two love each other and Chika even asks for more and wants Yamada to be his exclusive stalker. That scene at the cafe was so cute LMAO!
(im also questioning my sanity when i wrote this...but ig i was extra tolerant coz chika wasnt all too against it
Ore to Omae no Stalker Boushihou