DEAR ABBY: My sister lost her husband a year ago. She has three grown children, but she has a fractured relationship with her 30-year-old daughter. I am heartbroken because I have two daughters and I can’t imagine what my sister is going through. My niece was close to her father and has thrown in my sister’s face that he was her person and she told him everything. My niece and I have a good relationship, and she confides to me things she does not speak to her mother about. I am debating whether to speak to my niece to get a sense of what her issue with my sister really is. My niece blames her …