Gempeatea , I had the same response to suggesting counselling. No way would he go because he had decided it was over, I had no discussion, no choice.
I said he owed it to young DC to do whatever it took to try and work things out, to attend counselling, to keep talking. It was an outright no, no point. Very cold and callous. It’s the complete turnabout in character/behaviour that is so shocking and hard to deal with. Then they can’t understand why you don’t want to be their friend. They expect you to move on as swiftly as they do.
The trauma and devastation it causes when they leave with no warning is, as you say, unbearable.
Arnold, yes women do it too. A male friend was treated the same way by his wife. She said he was paranoid, when all the time she was after other men.
Time as always is the only healer and you come to terms with it in some way eventually but it leaves a scar (for me anyway!) so I don’t feel I could ever trust again. Time will tell.
Gem, you sound like you are moving on and dealing with it in your own way and that’s the best you can do.