Perhaps your son went for a hard working, ambitious woman who was independent, so when he started laying out his demands on how a woman should be (sounds like he thought of her as property) she was smart and independent enough to see what a bad situation Your Son was creating. Quite frankly his is responsible for ruining his engagement by believing he is spiritually justified to dominate his wife, not be her protect and leader.
And when he saw how that backfired and that a good woman knew better than to put up with that crap, he switched gears and found a woman who is less busy and ambitious. He still wants to maintain this fantasy of control, so now he tries to talk as if he is expecting his new woman to do nothing, as if by her acting how she was before she met him, he can show his illusion of control by saying that's what he expects. Because he knows if he starts laying out a list as he did before, he could lose another woman.
I feel that, until he realizes that it's not his place as a husband to control, but to lead by example and encouragement, that no relationship will ever be happy for him.
Real leadership, even as a husband, isn't about making demands and being in control. It's about knowing the line between listening and considering the words of others vs when you need to take a stand, not for your own power trip, but because stand up leadership is needed.
At some point in his life he got the wrong idea of what leadership means. And when he tried to stand up and be a 'leader' (or his fantasy version of what a leader is) someone stronger put him in his place. Now he's weak and afraid and wants to appear in control, when really, he knows he isn't at all in control. Not even being a leader at this point.
Worse yet, you know nothing about this girl, yet you are quick to get in her face and question her life and lifestyle with an accusing finger. Rather than focusing on the differences you have have you tried to sit down and get to know her as a Person, and not as a let down decision that your son has made to be with someone so lowly and undeserving to be in your family?
I'm sure you'll say that's not what you're thinking. But that is Exactly how you sound. I feel sympathy for her if she does marry into this family, to be quite honest.
When i was 20 i made a Very Very bad decision in a woman i chose to date, get engaged to and almost moved in together. My parents were well aware of what a bad choice is was. They didn't like her much because of the circumstances, i won't get into. But when she would show up, she never had a clue my parents had anything against her. They welcomed her into their home. They were prepared to welcome her into the family. They hugged her. Made sure she felt involved and taken care of. Because they knew that, bad decision or not, if i picked her, then she still must be a good person. Rather than making her feel judged and rejected, she felt welcomed. As did my brother and sisters. No one quit talking to me.
It really speaks poorly of your family that they are willing to nearly disown their own brother because they disagree with a choice he's making.
Though that makes things more clear. Family acceptance is based on doing what you're told. Making choices everyone approves of, and if not we'll make sure you know it loud and clear, and walk away from you like you mean nothing. Same thing his fiance did. All these people are hard working, ambitious people.
Looking at it from that point of view, is it really any wonder why he would go the complete opposite? Perhaps he figures if hard working, ambitious people have conditional love and acceptance, maybe someone the opposite will be more accepting of him.