I would say unconditional love, patience, understanding, communication, and honesty.

Honesty, communication, and lots of good sex...oh yeah! Good samich making skills don't hurt either

Most of these things!

I picked a few choices, but I think the most important of all is Honesty.

I voted for communication because it encompasses so much of what makes a successful relationship work. If you can't tell your partner what you like, don't like, your fears, share your successes, tell them your hopes and have them respond back in kind, I think the relationship suffers. I look to my father as a perfect example of what NOT to do in a relationship. He never did know how to communicate, to share his feelings in an open and honest way and in the end the marriage crumbled. It's not always easy to communicate with your partner and it takes courage sometimes, but it really does tend to strengthen a relationship in my opinion.

Honesty is my #1, followed by respect and compromise. Without those, not going to work.

So many things go into a good relationship. One of the very important things is to keep each other in the loop with most things having to do with your relationship.

Honestly it is a combination of all of those things.