Ask Allison: My sister-in-law monopolises my wife with her problems – how do I ask my wife to put us first?

Question:My wife and I are married with small children and two very busy careers. Putting it mildly, we are stretched pretty thin most of the time. My wife has one sister who is single and without children. Her last long-term relationship with a boyfriend ended badly, and in my opinion, left her a very bitter, negative and angry person. She often comments how this boyfriend “took the best years of my life” and left her with nothing to show for it.