Getting surrounded by children is usually a quick way to have all your thoughts thrown into disarray. It’s almost as effective as being buried in a puddle of kittens/puppies. Gabrielle could have certainly used it as well.
So why does one of Grand Order’s fearless masters have a relatively generic issue of bottling up emotions and having breakdowns in the middle of singularities when no one is looking? Because I hate writing Mary Sues, that’s why, even if the game has essentially set them up to be exactly that. It’s hard to relate to any character with even the smallest bit of magical prowess, but every bit to make them feel more human helps. This is also her first primary singularity. That, coupled with being the vanguard for the Oni Fiasco that incapacitated so many servants at once, would smack the self-confidence of the more emotional master with relative ease. As far as I’m concerned, it’s a plausible breakdown.
If you’re wondering which servants vouched for the two knights, they will be revealed in time, though it should be relatively obvious who it was.
You may feel Dantes got far less damage than Gawain, but it’s not the case; It’s why the Avenger, one of Chaldea’s trump cards, has to be sent back to heal where Gawain was allowed a rare combat management. That, plus the fact it pretty much neutralized two casters from doing anything else for a long period of time, makes in-field repairs a really inefficient idea.
Plus, keeping someone who can move around and attack at the speed of thought is a tad cheezy plot wise.