Your partner reinforces your ideas of the direction your life should take, which is a relief for you, to say the least! It can be difficult sometimes to constantly push forward through life, and that makes it extra nice to find a partner like they are for you -- someone who encourages you and understands you, and helps you find your way. You feel as if they're your safe harbor, your teacher and guide, your inspiration and your best cheerleader.
You return the favor by serving all those roles for them, as well. Something about accompanying you on your journey actually helps them along theirs. You help each other out on a regular basis by giving each other advice -- and it's sound advice, because you understand each other so well that you really have a good idea of where your lover needs to go next. The level of respect between you really helps you listen to that good advice and take it when appropriate! There is a feeling between you that you're traveling life's many paths together, and that helps cut down on the confusion, the loneliness and so on. You help each other find a positive way to express yourselves and focus your energies. If either of you is floundering in any way in your personal life, this relationship helps you calm down, gain focus and find a direction.