RGM.... maybe with some people that's true. Like my husband may have known (even when he insisted he was certain and never admitted feeling otherwise), but I believe my friend was 100% certain, and she never once expressed feelings that she was making a mistake to me or other friends.
When she and her husband were still living together (but had been "separated" for over a year), she even helped him pick out clothes for his first date!!! She had no feelings of jealousy or anger whatsoever. She truly believed she was making a wise decision and felt it was time to "make choices" for herself for once (after spending years doing things for others... a common thing you'll hear from women in MLC).
I think what might make it so hard for these people is it TRULY feels right. And I think they are very good at convincing themselves it is. Unfortunately, it's not until they live through it that they realize the result of their choice and can clearly see what they had.
The lesson you've learned is a good one. If someone wants to go, send them on their way. RMG, did you do that? Are you angry?
You take care too, Running
There is no arriving, ever. It is all a continual becoming.