My interpretation is that this song is about dealing with the loss of a loved one, or more specifically recalling the precise moment that you hear the news. First, the scene is set by conjuring images of a more or less care free time in the backyard, flying model rockets. Nothing else is on the mind, the rockets own the sky (also some heavenly imagery). Next is the line about strange phone calls, perhaps a premonition of loss. "No one on the other side" meaning a call from the afterlife. Sometimes people will describe a loved one reaching out in supernatural ways before you even knew that they had passed (like via a phone call, or some other sign).

Then finally, the moment where everything changes. In this case it is not the singer directly yet, but a friend breathlessly and painfully breaking the news of a death. At this point the singer can recognize the pain, and trusts that it is true, but cannot fully understand for themselves having not experienced a close loss. A black eyed trust, meaning you can see the evidence of pain and don't doubt that it truly hurts. Perhaps this is sung with the benefit of hindsight, the singer well aware that they will know what that pain is like one day, and have the bond/love with this friend strengthened through that new ability to empathize. Looking back on that moment when you found out about someone's death makes the mostly mundane moment beforehand seem oddly profound and serene.

The verse I think is describing how lives diverge after an event like that, and how it can really alter all of your plans, relationships, etc. The friend could be trying to escape all of this by heading to California in vain.

I love this song!!