Ah, gotcha.
So after you've put your everything into a relationship, a marriage, building a home, paying the mortgage for your life together, choosing the other half that your children will be, living and tailoring your life building towards a joint future for your family.... He turns round and says "I'm leaving you for Sandra at the office" and the obvious response is "Why would I be sad? He's obviously an arsehole, so that's that"
Wake the fuck up. People lose homes, families, full custody of their children, finances, their expected future. It's not ok because "well he's a dickhead though."
I have women at my charity, in food crisis, fuel crisis, housing crisis because they've been left high and dry with all the children. I'll just ask them why they're sad shall I?
Then there's the known abuse, gaslighting, and all that hideousness that tends to go hand in hand with affairs and their cover ups. Slowly chipping at someone's mental state, making them think they're going crazy. But it's ok, move on, because it turns out "he's an arsehole"