Introduced to Cassandra

So now my partner has been reading everything they can find on cassandra syndrome and apparently using this to lay at my door, and if I say anything I get 'thats exactly it, youve just proved my point'. I am in a no win situation, not that there was anything to win.
So this time it stems from something said that led to a reaction/outburst on their part about not telling them what to do. - background: Theres something to do (of no consequence to me), and theres certain paperwork that needs to be taken (and may of needed going to get as far as i knew), so referring to this however it was- 'dont forget' or you'll need... or however it was mentioned, - was wrong, undermining, telling them want to do or whatever. It is something anyone wouldve said, but pointing that out only got the response its not that one thing its the bigger picture and the one thing on top makes them blow. But i say nothing - its wrong,- I say its unreasonable to react like that, then i'm accused of always shifting the blame, and now theres knowledge of cassandra symdrome with references to things people have written, which I'm told is exactly proving cassandra syndrome etc.

Its a minefield