Job hoppers are not evil
Looking for stability is very common amongst resume readers and explaining hops can be a task for the faint hearted. Fear is so real that timing the job out for resume sake is a recommended behavior even if that amounts to a greater sin.
People sell their labour till they find something worth their heart. Winning hearts isn't what most Organizations are built for, so attrition should be a surprise. We camouflage this Organizational inability by making working professionals feel morally obligated to prefer stability over their own search for fitment. Naturally, it doesn't work.
Wiser employers quickly begin adopting ways to find culture fit, it has a better chance of making good match than functional interviews. Remember, people are not always clear about what they are looking for, so there is a fair chance of creating an impression and holding them long.
Some ways worth incorporating in your talent acquisition strategy* could be:
1. Coffee table meetings are simple colleague level interactions with shortlisted candidates that allow existing members to spend time with the candidate. It's a good dip stick way to find match.
2. Carry along evaluation is an on the go interview that runs through the day or even more than a day where you carry the shortlisted candidate along your work routine. Beyond an hour, this hardly remains an interview and nothing beats this method if you can pull it off.
3. Eject incentive is a substantial reward you offer to new joinees for taking an exit decision within a few weeks of joining. By doing that you cut the fake journey and save huge amount of further investment. You rather do the hiring cycle again than live with someone half hearted.
Once you start thinking this way, you'll be able to figure so many other methods of helping misfits hop out without much moral hullabaloo. You'd do both a huge favor.
Eventually you'll find a fit and she'l find her calling.
* Warning: Try these at your own risk, suggestions are unconventional.