The big thing is supporting your training schedule; I never ask my guy to change his training schedule, and he never asks me to change mine. We also support each other's nutritional needs, and don't try to get the other to eat something off diet. And, listening is a big one; sometimes, you just need to rant about injuries, plateaus, or when you have a great workout, and having someone there who truly listens to you and understands what you're going through is wonderful.