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 Logic: If Amy doesn't choose Aaron, he ends up with Abigail. If you take into account that Aaron and Abigail already broke up in the past, (likely that he broke up with her, since she's so desperate to get back together with him), it seems likely that they will break up again presumably because Aaron realizes they have little in common or he recognizes her true nature.
Hollywood Homely: Amy occasionally remarks how plain and average she is, but there's nothing to indicate that she's any less attractive than Abigail or the rest of the cast.