There was a relatively recent interview (a year ago) with Charlotte Hatherley which is quite extensive and the first part focuses a lot on her time with Ash:

https://www.youtube.com/watch?v=0Atxe-phKLs

It is a very interesting listen and it seems the split was more or less inevitable.

I saw them live one or twice during the Meltdown tour and remember thinking she kinda was just there and not really into it that much even though she performed well if that makes sense. So the split actually did not break my heart when it happened but in hindsight (also based on what she is saying in the interview) both sides probably have a lot of regrets.