I am not excusing Yelp, but in most countries this is fire-able offense. In EU my friends were in similar situation and they had to go to work. She got half-day off on very short notice..
I don't know about the rest of EU, but I currently work in France and I'd be shocked if someone were fired because they took half a day off with little to no notice for serious health or family reasons. If anything, the company would be sued in a heartbeat and almost guaranteed to lose. I worked in the UK for a few years, and have had to take days off with no notice - to attend a funeral, say - and no one even though…
In this case, what we can guess it looked like from her manager's point of view was: she kept taking days off, with excuses that didn't seem to make sense (can't find car keys), and now she wants to take three more days off.
Without trying to blame anyone, I feel bad for her and hope her boyfriend recovers.