If your employer is trying to blur the lines between work and friendship, establish a line you can hold to while still doing your job
My boss is great to work for, but she has a bad habit of calling me at home at odd hours just to chat. There's always some small work issue that she mentions in her calls, but it's mostly just chatting that we could do anytime at work. How can I get her to back off and respect my free time?
First off, it's great that you have a friendly relationship with your boss. But I do understand that if her "just to chat" calls are too frequent or tend to cut into your off-work hours for non-urgent reasons, that could be a problem. My advice is to say, early in each of these calls, "You know what Marilyn, I'm afraid that I only have about 10 minutes to talk right now before I have to dash out. Should we take care of the work issue first?"
That way, she will know that you're happy to take her calls when they're work-related, but don't really have the time or inclination to talk about regular "life" issues when you're not in the office. And if you say you only have 10 minutes, stick to that. Don't stay on the phone for half an hour because that inadvertently sends the message that your 10-minute deadline wasn't real, or that it didn't matter.
Of course, there might be times when there's an urgent situation at work and your boss has to call you after hours. It wouldn't be great for you or the company if you avoided those calls or cut them short, or if she felt she couldn't count on you when she really needed to. But if your boss is becoming just a bit too comfortable shooting the breeze when you would rather be enjoying your free time, it's perfectly fine to wean her from the practice by keeping those calls businesslike and short.
If your boss doesn't get the hint after a few 10-minute warnings, you can, of course, get a phone with caller ID and simply avoid her calls altogether (though that may not be foolproof, because her number could show up as "blocked call" or "restricted"). But I would recommend being straightforward (but still friendly!) with her and gently send the message that you would rather not get calls at home except when there's something important afoot on the job.