I think how receptive they are is dependent on their mood/feelings/things outside of the relationship etc, as there have been other times I've told her how I was feeling about things and she didn't explode at me.
Hi Beren2016. I'd like to elaborate on CMJ's excellent thought. I've recently become more aware of my wife's "BPD cycle" and how her responses to certain questions / topics may be very different at different times. Though it's not 100% consistent, my wife tends to move in one to two week cycle's in terms of episodes, being normal and sweet until something suddenly explodes when she needs it to. I believe when she's in the ready to be triggered phase, just about anything could do it as long as the timing is right (last time it was a cake I didn't buy her). When she's at a low trigger phase, I can ask for something big, such as her taking care of the kids one extra night so I can join a music class, with no bad reaction whatsoever. Problem is we rarely know what phase they are in.
Everyone is different and this might not describe your gf at all. And it's great of you to make every effort to communicate in a way that she won't read blame into what you say. But my point is that depending on how she functions, there may be times where she reacts the way she does no matter how you communicate. It's best you don't blame yourself for some communication failure in this situation. In some cases the non (person without BPD) may be the trigger, but we are not the cause. I believe that matter how calm I keep things, my wife's BPD finds a way out no matter what.
Does this sound anything like your gf?
All the best
~ROE