Burg, if your kids played in a band every single Wednesday night and on one particular Wednesday night, you saw a stranger get hit by a car, there was no one else to accompany the stranger to the ER, AND the person's life was in danger, I would expect you to go to the ER.
OTOH, if your kids were being awarded a Grammy or playing at Lincoln Center on some Wednesday night, and your gf was a regular visitor to the ER for migraines or something, I would expect her to go alone on this particular Wednesday.
My bf told me from day one that his kids and his mom would always come first. I understood that that would be the case if we were bf-gf. Marriage might have changed that, but maybe not.