Two particular points of interest today. Garfield regularly trades in schadenfreude gags, wherein Garfield takes pleasure in Jon or Odie's pain. This visit to the movies provides a sweet-natured and related counterpoint. It's not Liz's sadness that gives Jon happiness, but her need for comfort, which is a natural byproduct of sadness. There's nothing insidious about taking pleasure in the ability to be there for a someone in need, but it is a minor human failing we do not usually admit. In more dire circumstances it is better known as the sin of pride. But Liz is not hurt or sad on a soul-shaking level - the reasons we attend weepy movies are the reasons the Greeks produced tragedy, and ultimately cathartic; the audience in their own way is happy because of their willful immersion in superficial sadness. Because of this we aren't concerned that Jon's exhibiting sociopathic behavior and feeling gleeful while others weep, rather there's a wistful little joke about a man unaccustomed to a social touch feeling his way in the world of interpersonal contact.
Audience Reaction Studies
Whatever the movie is about, surely a bittersweet romance, a real-life drama is happening in the theater, and goes unnoticed by all but the knowing and/or leering elderly woman. The rest of the audience is rapt, and from the neckless soda-sucker to the neck-braced popcorn-eater to the fright-wigged aerobics instructor, in true Garfield fashion, no one looks like they're enjoying themselves.
Besides Liz, who I hope is talking at normal volume during a movie only for expositional purposes, no one is communicating the emotional effects of the film so well as the redhead in the turtleneck. Cartooning crowds of ugly people without distracting from a simple joke is a tricky tightrope. Her one-handed pantomime makes her the only audience member vying for our attention in the packed frame. Also I'm pretty sure her date is one of the Fabulous Furry Freak Brothers.