The novel ended at the end of the sequel part, where Katarina realizes this is her "life" now and that the game had nothing to tie in with her actions due to them being so different, but it pretty much ends just like this manga with the same conventional stands for every character like her having a husband and confirming it and all that.
So to be quite honest if the manga ended at this, it would be fine, even with the "sequel" coming out to make for the next arc.