Jealousy.

One day we're going to find ourselves in front of a camera and it will be 3 in the morning.
We'll be talking quietly about the hardest part of being in love but we'll have no idea how we got there.
"Jealousy" we'll say.  Almost in union, in the same monotone as each other.
Your hair will be a mess and your head on my shoulder.
I might kiss your forehead and tell you you're predictable. 
"Jealousy" you'll say.
And the camera battery will die.