These days, I actually get anxious whenever a romance manga starts to progress suddenly.
I have been backstabbed by sudden axes way too many times after sudden progress.
Please don't suddenly end after they get together. I'm tired of that cliche.
My rule of thumb is to do the tankoubon chapter math, since axe-kun only strikes at the end of a book unless something absolutely horrendous happened (after all, axe-kun usually strikes because sales are crap, and even a completed bad-selling book is better than an unfinished half a book you can't sell at all).
This actually forecasts
extremely well in this case, since it looks like this one is running 8 chapters to a book, so being chapter 17 means we are at the very beginning of volume 3, which is pretty much as safe from a sudden cancelling as it gets.