Hi & welcome.
Your situation is eerily similar to one I've recently experienced with my ex. I'm sorry that yours is further complicated by the fact you are married.
We had been planning to move to a bigger house and start a family, she was leading all of this.
I can’t understand how we can go from that one week to this the next.
This resonates, we currently rent an apartment together but she is in the process of buying her own and wanted me to move in, we were in a furniture store not so long ago and she was recommending what furniture I should get for my things. Not long after she called it off.
After dumping me yeah she pretty much immediately signed up to the old dating site where we first met. She's up until the early hours chatting to other men. I'm pretty sure by now she's lined-up my replacement for when the lock-down is lifted. The speed at which they do these things is incredible! Blocked / Deleted me immediately from social networks along with all my close family / friends. Bizarre, when they did the dumping. Perhaps it's symptomatic of their 'splitting' & de-valuing, this form of erasure, I'm not expert enough to know.
I guess, and I think it's true in my ex's case she felt deeply unloved & ignored. I've been spending a lot of time on work projects and studying and I know she felt neglected by that and I felt incredibly guilty but it was a difficult balancing act, unfortunately spending quality time with a loved one doesn't pay the bills. I had always encouraged her to build her own network of friends/ social life and not rely on me so much for her happiness. She started looking elsewhere for social interactions, but I think in my case she just wanted to explore those interactions at a far more deeper level.
Maybe you need to try and explore what issues there are in your relationship? Do you make enough time for her? Do you communicate at a level she can relate to? In my case I think we may aswell have been speaking different languages during conflicts.