This might not solve it, but; make sure you're both on the latest version of Origin (that came out last night or this morning). I'd shut down Origin completely (make sure the tray icon is gone), start it back up, manually check for a new version, etc.
Sorry if that doesn't fix it. You're not the only one affected. =\
Yeah, we've both taken steps like that where we've uninstalled and reinstalled Origin to the latest version. Weird thing is, it only does it between me and him. He has another friend who he can interact with just fine. I don't know. Hopefully EA fixes that stuff at least around the time the game ships.
You guys made a hell of a game though, I've been loving it so far. This is coming from a guy who was really getting burned out on the genre, but this breathed new life into it for me. ^_^