DEAR ABBY: My husband and I are planning a cruise to celebrate our 30th wedding anniversary as well as his retirement next year. We invited my brother and his wife, “Rita,” to join us. Because my brother has always wanted to visit our cruise destination, they accepted. Rita then shared our cruise plans with her brother and his wife, “Jewel.” Jewel expressed interest in the destination and said she wouldn’t mind going. In response, Rita welcomed them to join us! When I was told this, Rita said her brother doesn’t like cruises and probably wouldn’t want to go, so I just let it go. Still, I am an…