RSD

How do I help my partner who has RSD? The RSD  incidents get extreme from me saying normal things which trigger them because of their insecurities and sense of failure. 
 

I am constantly trying to help and support them. It's draining because I have to continually apologise for saying what would be normal things to anyone else. Friends notice how they behave and say I've done nothing wrong. 
 

They lash out with cruel words, give me the silent treatment, go off for hours and then I wait until they come back to be told off. 
 

it happens very regularly. It's impacting on the way I feel about them. They tell me after that it's their fault. Sometimes it resolves relatively quickly but other times it goes on for hours or into the next day. And I never know what will trigger them. I really try and want to say the right thing but just keep upsetting them. Don't know what to do.