Ugh - I'm actually grateful my ex hooked up with his current wife about a year after we separated. But she was also young - 32 to my ex's 51 - and my boys (18-23) were pretty uncomfortable with the fact that she looked more like someone THEY would date than like someone they could picture with their dad. Still, they didn't have to hear stories of him dating. They get along ok with her now (she wasn't an affair partner thank god). But their whole view of marriage is skewed, because they thought they grew up in a home with a stable marriage, and when the rug was pulled out from under them, it really does leave them with a feeling that nothing can be counted on.