DEAR ANNIE: I’m retired, which is fine, but not having to go to a job only leaves me with more time to live with my problem. It’s one that I’ve had for a very long time. My wife’s sister came to live with us, and I got along with her very well, and when I wasn’t working, we spent a lot of time together. We had a lot in common, which led to me actually falling for her. I doubt that she feels the same way, and I never told her or anyone about it, but that doesn’t make it any less of a problem. I know it has affected my marriage, but I just can’t find a way to fall out of love with either one. Sh…