I honestly don't know if this was a meme/single-page bit, or something longer. It had a girl who'd started dating a boy, who was basically a yandere. She keeps trying to hit him with various yandere lines, but his replies always shoot the threats down and assure her that there's absolutely nothing for her to "yan" for. If I remember right she was fairly frustrated by this. Like, for instance, if she makes threats of what she'll do if he cheats on her, he just says he's not popular so that's not even possible.

Flag Capture in the First Move
I believe, chapter 5 from this collection is what you're looking for