"You know - we need to really do this more often. It was really nice."
"We should show each other and us being together more appreciation than we do"
i may be very wrong,yet you asked for what anyone thought could have triggered her.well this is what it seems to me
your suggestion to do it more often might have seemed her that you werent happy with her 'when things were within the normal schedule'
but what i think your wife really might have got upset over was the last thing,she could have easily misinterpreted as you criticizing her that she never showed appreciation to you,that you werent happy with her and her reactions and her amount of appreciation towards you.
you said a very positive thing,but people with this disorder mostly see many comments as negative,or often look for criticism.
if it was me,i'd let this blow over,because explaining,arguing or justifying, DOES NOT HELP,but looks to the person with BPD as 'making excuses' or 'admission of guilt' atleast in my experience.
well hope i helped a bit.