Maybe I'm burned by past experience, but if somebody started acting that friendly to me without us really knowing each other, I'd be really suspicious of their motives.
Everything has to end, and better to end a story like this on a high note. I hope the author has done a good job of that.
Thank you, Sleepy Fox, for your hard work!
Miku's face on the last page. She's happy for Yotsuba, and for Fuutarou.
Even if her own heart was broken, she is mending the cracks with gold. I am satisfied with this.