DEAR HARRIETTE: My sister just moved into a new home with her boyfriend of 10 years. They have three kids, and he is a really active father. He does everything with the kids, so she doesn't have to do much. Even after he has provided a home and helped her buy a car, she continually complains that it's not good enough. She says it's not a luxury car or the house isn't big enough, but it's all bette…