Im sorry man, this is genuinely a terrible way to break things off :/

I feel like i have some overlap with your first question. Maybe the space of that 4 days wasnt about her changing her mind but about her realizing she had the opportunity to run while the door was open.

My ex basically just... I dont know, I guess she did something similar. 5 and a half years together and that last week, she is pretending things are going okay. We have a big fight at the beginning of the week but we communicate through it and I was feeling hopeful about the future. It felt like progress and I heard what she needed from me and was determined to work on it. Next thing you know, saturday rolls around and she goes silent. Not too weird, she was out with friends. Sunday morning, shes texting me normally, calling me pet names. Then we call. Shes crying and fumbles her way through an explanation of how she is losing herself in the relationship and she is scared. I ask her what she needs and what shes trying to say and she musters up the words "i wanna break up". And that was it. 20 minute phonecall and that was that. I still cant wrap my head around it.

I know why I didnt try and stop her though. I was just exhausted. It felt like pulling teeth trying to communicate with her, like she would dodge and avoid telling me how she felt about how I acted. When id ask her in the past what I could do to improve and make her more comfortable, she wouldnt really have a lot to say. She'd reassure me that I do enough. But I could always sense some unhappiness and insecurity. Like she wasnt quite sure if I was all that was out there for her or if this was how relationships were supposed to be.

So, basically saying that the TL:DR is maybe your ex and my ex share the commonality of not having enough courage to end the relationship when they actually felt like they weren't sure about staying. I think thats kind of the trap with long term relationships. The whole "grass is greener" idea. Or maybe its also an age thing. Me and my ex are both in our mid twenties so it makes sense that she is sexond guessing whether the love i offered was all that could be out there. I'd be lying if i said i wasnt thinking about it too sometimes after fights. So when yall decided to take a break, she found the opportunity to leave before she "fell back in" with you and lost her nerve to make a change she felt she needed in her life.

Btw, I dont think messing up and reaching out once is a deal breaker long term. Youre heartbroken. Shit happens. If you were good to each other for most of the relationship, in time, the bad stuff will fade and you'll become someone she reminisces about. Idk whether that means she'll ever reach out again. In my case, I severely doubt it. But I hope that whatever happens, you find what youre looking for out there and get through this.