Relationship with lords is either heavily bugged, or not fully implemented. I'm not sure which it is.
You no longer get a boost in relationship for being allies in battles with them, for riding in to save them from a close battle, or rescuing them from enemy lords who have them captive. You /should/ be getting a boost in relationship every time you fight alongside each other. Military campaigns are supposed to be the easy way to get in good with the local lords.