Finally! I found it! From You Don’t Love Me Yet by Jonathan Lethem (far from his best, but certainly memorable enough because of this part): “I don’t think it counted for that much one way or the other. We were each other’s astronaut food.” “What’s astronaut food?” “You know, stuff in little packets that you keep laying on the shelf. The people you imagine you might be with but you know you never really will be. The people who if you’re in a couple and you’re a little bored or restless you meet them for coffee a lot and the other half of your couple isn’t really thrilled about it. Or if you’re single they’re the people you’re keeping on a mental list just so you don’t feel like there aren’t any possibilities. Friends who are almost more than friends, but, really they’re just friends. Astronaut food, bomb shelter provisions. Sometimes you even fall into bed with them but it doesn’t count for much. It’s always a mistake to try to get any nourishment out of that stuff. But not a big mistake. That’s the beautiful part, how the stakes are so low.” “Only if everyone agrees they’re mutual astronaut food.” “Oh, absolutely. You can screw up your astronaut food a million ways. Even just letting them know. Though they sense it at a certain level, nobody wants to be told. The worst is when someone falls in love and then gets all righteous about breaking up with their astronaut food, as if there’s anything to break up about.” “What about the situation when someone is just acting like they’re only astronaut food, but really has hopes of something more?” “Yes.” Check out the entry at urbandictionary: http://www.urbandictionary.com/define.php?term=astronaut+food