So yeah, this got adapted into the first half of the very first OVA made for this series. It was a neat initial peek at the 'Season 2' phase of the show, but, I'll be honest, the idea of a near-sighted person leaving glasses on a precarious windowsill to go grab a cleaning cloth? I'd have just kept wearing the glasses, walked to the cloth, grabbed the cloth, and then taken off my glasses and cleaned them right there, put them back on, be done with it. Why would you just take them off and leave them somewhere unless you actually had to remove them for something like going into a pool or shower? It's a contrived excuse, to me.
But, well... it still gave an opportunity to see Shu talk seriously about things, and point out that Ruri needs to ease off on pushing Kosaki to confess her feelings, just because she found it 'frustrating' watching her friend flail.
And Shu is probably also aware that Raku and Chitoge are getting closer during all of this, as well, and realizes Kosaki could ruin all of that. He might even be aware that the closer Raku and Chitoge are, the safer the gang situation will be. He's a surprisingly perceptive fellow. The more Kosaki tries to butt in, the closer the entire town will be to devastation. I feel like we got scarily close leading up to the cultural festival and the play. If Chitoge hadn't been needed to become Juliet for the play at the last minute, the core relationship might have continued to stagnate like that until the gangs realized they weren't together anymore and started tearing up the streets.
And Raku may well have been the first casualty at Claude's hands. The people cheering for Kosaki seem to keep forgetting there's a potential gang war looming if that girl dares to disrupt the core relationship. So long as Chitoge has hope he'll choose her, war can be averted.
Ruri had been a harbinger of doom up until this point with her meddling. Her ignorance could have destroyed everything.