Great start, great characters, awful finish. I assume it got axed, but even then, this is an awful way to end a manga.
The premise isn't too horribly original: struggling mangaka gets a new editor who is quirky but dedicated, and falls for them. The genders are reversed from some of the other struggling mangaka stories I've read before (Comic Studio, Koimoku), but the basic ideas are the same: to make it as a mangaka you need to pull all-nighters, you need to pay attention to detail, you need to be creative, you need to balance your artistic impulse with the readers' preferences,
Pen to Chocolate starts out a pretty good version of this story. The mangaka and the editor are both likable characters, with their own little personality quirks that make them funny and interesting. The mangaka's attraction to the editor is explained well, despite the fact that he is pretty much a geek and a slob. They do a good job of introducing and discarding other romantic interests.
And all the while, the editor is slowly helping the mangaka become better at her job. Supposedly.
Except that then the last few chapters hit. And everything we thought we knew about the mangaka's career trajectory turns out to be wrong. And then there are time skips. And more time skips. And suddenly they try to pull out a "happily ever after" ending, except the author never explained how it happened and also left the romance completely ambiguous.
I understand that sometimes manga--even otherwise pretty good manga like this one--get axed and need a rush-job ending. This is a case study in how NOT to do it.