I've had that happen to me. It wasn't because of the length, it's because I took so long writing my post.

So if I remember to suspect it might have timed out, I save copy the entire text to my clipboard ( or copy it over to another writing app) before hitting the Post button. That way I don't lose it. If I remember beforehand.
I don't know whether she is seriously disordered, not enough behavior patterns reported so far, but one behavior pattern that is possible here is you experienced a predictable
idolization phase but once you became obligated to her then the newness wore off and her interest in you has faded, perhaps even
rejected you.
Just as background, even normal marriages can start out hot and heavy then settle into a less active relationship. Think of going to the adventure park and riding the new roller coaster. First time is super exhilarating. After a few rides or even visits the next years, not so much.
It could be sort of a reverse
push-pull pattern. There is a dance to this, one book was titled, "
I Hate You, Don't Leave Me".
It's happened 3 times already to you. Do you work it out together? Or do you acquiesce and let her control the return?
How extreme is this? Is there "high conflict"? Or more like she's just lost interest in you?