This is John's story, so it's fitting that he be the one to tell it to us. Did you notice how it's almost like he's talking directly to us, like we're his friends? Take when he's waiting for Marisol:
I looked out the window trying to guess which people might be coming into the store, which girl might be Marisol. But as people kept zooming past I got a headache, a twin to the one I had the night before at dinner. (2.3)
Notice how he's telling us what's going down (he's looking out the window) and how he feels about it (wondering who she might be, getting a headache). We get an all-access pass to what goes on with John. The downside? We don't get the stuff that he's not a part of, or that he doesn't understand. So when he tells us about his parents' divorce or a fight with Marisol, it's a little one-sided, because we only get a window into his mind. And we know he's not necessarily the most accurate at assessing situations—otherwise he'd never go in for that kiss.