I don't want to continue ranting about this on Niomi's thread, but as someone who was recently blindsided, I've had my therapist confirm that it is indeed a traumatic experience. One day everything is great, we're building a future together, and he's making plans to visit me, and the literal next day he says he doesn't love me anymore and we shouldn't be together. It's the biggest mindfuck I've ever experienced, your whole reality is denied, you've lived in a lie, you're questioning everything about yourself and you're wondering if this person ever loved you in the first place.
There are lasting consequences to being blindsided, I can only imagine it's worse in Niomi's case since she was trying on wedding dresses two days before Joe broke it off. She indeed lived (and still lives) a very coddled life, but the betrayal and heartbreak that comes with being blindsided by the person you loved most in the world is nothing short of traumatic.