@EveSix
I don't feel comfortable sharing, but yes I have.
From my observations both from my/our own therapy sessions and from talking to other people, most of the so-called work is to get the other side to be 'reasonable' and change. But that rarely happens, so the person then thinks well I've tried so hard and gone to therapy etc etc, and nothing has changed.
The truth is that the only real point of therapy should be to learn to let go and accept. Nobody is perfect, and no matter whom you end up with, there'll be thing that person does that annoy you, and things they should be doing but don't. The real question is do you get enough value out of the relationship that you can just overlook these niggles.
I'd say that if people were honest with themselves, the vast majority of the time they do. Take for example a husband who never does any washing up or whatever. That could be done by a hiring a cleaner for what, 50 quid a week? So is that minor problem worth throwing everything away? I'm talking when the husband provides an income, companionship, emotional support etc. You'll find that usually the benefits far outweigh the areas he lacks. And the same goes the other way around too.
However, what often happens is that resentment sets in, and instead of being easy going and accepting the partner isn't perfect, you just stew and seethe. Then you suddenly find yourself married for 20 years and you're strangers with mutual loathing. But it was so unnecessary, and if both partners would just have realised early on that they're not perfect either, and it's not worth jettisoning a relationship for that, they could have had a beautiful life.
The one good thing is that it's not too late. You can always reboot your marriage with different outlooks and acceptances, and really start living. In businesses employers will often put in much work and training to get employees up to scratch, because the cost of firing and hiring can be far higher than perfecting what you already have.
And it's not like her next partner, if she does find someone, won't have his own faults. We all do.