Eh, on one hand - neat to see she's taking initiative and this isn't dragging it on. On the other - that is an unbelievably forced way to make him decide. If you present this whole narrative of having to pick a gf over a friend, maybe don't actuate it into some dramatic decision just 2-3 chapters later. Axed series ending chapter vibes.
I don't think she's going yandere, the story hasn't been implying this. Normally you set these things up. Just generic jealously into shock that she has to compete for him.