Death Cab For Cutie - Passenger Seat Lyrics Meaning

I see it as the sudden realization when you know you are in love with someone. When you are in their presence and don't need to talk or entertain each other. You're mind drifts off and you think of something like shooting stars and satellites and you're not embarrassed to communicate what's on your mind. The only thing that matters is that you are together. Nothing else matters, not even the world. And whatever that person needs help you will guide them and support them always.