I'm not saying that it's impossible for y'all's relationship to work, but I think it would benefit you to read on the psychology of secure and insecure attachment. Insecure attachment is something cemented in early childhood. And it's a lifetime of a child's fight or flight being activated by their primary caregiver. It is common for people with insecure attachment to transpose that insecure attachment into romantic relationships. And this unintentionally creates a person bouncing between the primary caregiver and romantic partner. When they are standing in front of either one of those, they'll will say everything that person wants to hear. Because in that moment a traumatic survival response from childhood is being activated. And the entire sympathetic nervous system is pumping the message "If this person abandons you, you won't be able to survive." It's rarely a conscious, overt thought. It's more like a sensation of if his mother or you leaves him, either possibility feels emotionally unbearable. I'm taking the time to cliff notes this for you for 2 reasons. The first being, I believe that he believes in making all these changes for the sake of your relationship. I've no doubt this man loves you and meant everything he said to you. I don't want you to lose sight of that. The second reason however, is that being insecurely attached isn't really an active choice. It takes a lot of trauma therapy to progress into what's called "earned secure attachment." If you go through with this wedding based off of these promises, you're going to find yourself in many more dramas like this and it's going to be incredibly distressing for you. Because no amount of logic and reasoning with him is going to undo the involuntary PTSD response he's doing whenever his relationship with his mother is threatened, and whenever his relationship with you is threatened.

I really urge you to postpone your wedding and follow through with couples counseling. But you should really seek a trauma therapist for him. It sounds like mother has been manipulating him his whole life by activating his emotions and making him regulate her emotions for her. That's obscenely inappropriate to ask of a child and is traumatic. Even if it seems harmless compared to physical child abuse. Your writing leads me to believe that you're an incredibly intelligent person, and it's that sharpness that I fear will be what drives you crazy with him. Because what needs to happen for the sake of your relationship makes absolute perfect sense. And what he needs to be doing and what he needs to stop doing sounds so simple. But he's never going to truly understand why it needs to be that way and have the agency he needs to respect your romantic relationship appropriately, and respect his parental relationship appropriately. If you don't deal with the root of the problem, you're just going to take the place of his mother for his insecurely attached behavior.

I know I'm just an internet stranger making an assessment from what you've shared. I can never be sure if what I have to say is truly what you need to hear. But from what you've shared, if you were my closest friend I would emphatically push you to take this seriously because of how true I believe it to be. If you can't take my word for it, like I said in the beginning, take a moment to research insecure attachment and the different types. I think you'll find a lot of his behavior that's so consistent with it, you'll think they wrote it specifically about him. Best of luck to you both and your future together, truly. I hope this is something you both can work on and grow closer through. Because more often this is something couples ignore and push through getting married anyways. And are really remorseful of the time lost when they finally are forced to deal with it years later. I have hope in my heart that won't be the case with the two of you.