This is actually easy to explain:

Men are "rewarded" by being with women, so the crucible ends.

The crucible the source of all the pain of this author's article.

The crucible is the willingness for someone to change for something else because they know that they are not good enough as they are.

If someone already "has" you, they're less likely to change for you but enter into a natural complacent state. You don't train men like dogs because your attention is the treat. And if you try; he'll pick up on the tactics and resist, and you'll be stuck in a complicated relationship.

So how do you put a man in "the crucible"? Easy. Don't let him "have" you. Read books, hang out with friends, etc. Live your own life until you're married, and realize that he's much less likely to change after he's married. Change comes during the courtship without being in a "relationship". Don't give in to boyfriend/girlfriend modernity.

If you're stuck in a marriage with a guy who has rough edges, then you will need to declare your pain, and you will have to use authority figures (priests, God, etc) to help you communicate to him your urgency, to put him into the crucible and pressure him to want to change. You cannot "control" him and you cannot "train" him, but you have to appeal to his spirit and his optimal nature.

As for the "momma's boy" example in the article, that can be contorted to be a bad thing and that can be contorted to be a good thing. When women are jealous of mothers, it's usually symptomatic of a different issue. It should not matter how a man engages his time elsewhere, but how a man engages his time with you. Therefore, instead of calling him a "momma's boy", you call him someone who does not have the resources to commit to an adult relationship (or someone who does not know how to have an adult relationship).

But you can never be his trainer: you're the enemy and you're the reward. His friends or his siblings or his church has to do so.

And if you're one of the really lucky ones: he's a clear headed communicator and realizes his life is always in a crucible, so he'll always be willing to change.

But if not, you won't have the authority anyway, especially if you're already committed to him.

Just my two cents...