Random Triggers Scaring Me

I have been in quite a stressful situation recently and when times get to much, Rex my other alter, Takes over without warning.
Like the other day, All I can remember was being upstairs at my partners then the next thing I know, I was nearly out the front door, My partner was saying sorry because she had gotten a bit mad over time keeping or something and I had no idea or recollection of this happening.
I ask Rex if he had taken over, so that It was blocked from me and he said yes, do these triggers happen all the time to others and is there anything I can do to control it? Thanks.

The only way I know of is working to make communication better between you and alters. Once communication is clearer, negotiation and compromise is possible. That way there are less surprises.