Thanks for more details -- that does shed more light.
The other night we were doing some (productive...yay!!) discussions about what happened that night and she admitted that she was upset with me because I couldn't make her stop feeling the way she was feeling. I said "you couldn't stop yourself either!" lol and we chuckled. She agrees that she needs to take control of her emotions and that she needs help to do it. We agree that it shouldn't be me to help her because it's deeper than our relationship. Therapy! I love it...I go often and advocate for it even more. She has agreed that she would benefit from some help and I'm happy she was able to make that decision.
Sounds like in the end, the kerfuffle led you to learning some new things about each other and you both came to a place where you agree to try a new thing to handle it: Therapy to grow the skills needed when having a "deer in headlights" moment.
Be ok learning together and making mistakes together -- the more of these you clock, the smaller the next ones become. Even if kerfuffle? You will move it forward better until finally the kerfuffles reduce in scope and volume. Some wobble is expected.
Hopefully B will see that also -- some give and take and some ugh is normal. It doesn't have to spell DOOM anywhere. (If he just doesn't dig her, that another thing. But take it one problem at a time where you can.)
Hang in there!