Wise authors often end the series when this happens -- even if their readers get angry. Charlaine Harris and Yasmine Galenorn are two of my favorite authors who come to mind as examples. [I've read with enjoyment several of their series -- from Emerald O'Brien of the Chintz 'n China Tea Room to Lucy Bard of Shakespeare].
A chance book -- Thread of Fear by Laura Griffin, I picked up at the supermarket, gave me this insight. I was reading a nice police procedural that started after with baby being found adrift on the Gulf [of Mexico]. Suddenly, I was reading Thread of Fear all the way through, without switching reads. None of the other three books I'm in the processing of reading [including Lee Child] had held my interest. Oh, the MCs had a problem to solve -- a mystery in the case of a couple cops or threat to their life or both. But Griffin's character stole the show for me by having to make a decision that will change the course of her life -- more than finding a hunk to love.
Fiona Glass is an art teacher who moonlights as a forensic artist. No paranormal abilities here, she's just great an establishing a rapport with her subjects to create life-like drawings that catch perps. In Thread of Fear, Fiona is recovering from a romance-gone-bad with a cop only to find herself falling for the small town cop who hires her to draw the perpetrator of a cold case that the cop thinks is related to a new murder/rape. When the third victim appears, the plot line is off and running.
Oh, the personal decision. All the while she's caught in the investigation of the serial murders and falling for the cop, she's trying to finish "serious" paintings for a coming art show. Oh, the dilemma. She's trying to quit the forensic bit for the serious bit.
Yeah, the book has well-developed characters, plot twists, and a great small town vs city comparison in the setting [to make the decision more difficult, I guess]. But those craft skills weren't what kept me glued to the book over the week-end. It was Fiona's problem plus some humorous scenes complicating her decision. I give the book Four Stars**** because the plot didn't stand out from the common mystery paradigms. Still, a good read though.