These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Fridge Horror: Okay, so Lindsay, Elody, Ally and Juliet are going to be walking around with massive amounts of guilt. Also, her family and little sister will be heartbroken. And Kent is going to be left with a few hints from Sam, and not just much else. Let's just stick with the noble sacrifice angle, okay?
It's also possible to interpret that Juliet died as well, meaning that Sam's sacrifice wasn't as meaningful as it should have been.
Even if she doesn't save Juliet, she still becomes a better person and her death will likely cause a change in the school's dog-eat-dog social dynamic.