You believe she's cold because he says so. You believe she neglects him because he complains about it. You even find yourself wondering why she won't let go of a man who supposedly no longer loves her. Meanwhile, she may be at home making dinner, raising their children, and believing her marriage is worth protecting.
You've developed resentment toward a woman whose only introduction to you came through the husband betraying her.
Iโd rather climb Mount Everest in a bikini than be a stepparent. Iโd lick the N1 from Kranskop to Beit Bridge before I even consider a man with a child. Iโd pick up Tsekelele, put him on my forehead & run the Comrades Marathon before I ever agree to being somebodyโs stepmom.