Sex?

How important is sex in a relationship? Is it just as important as trust, and honesty? Or are trust and honest more important than sex?

I would place everything equal. Honesty, trust, sex, loyalty, communication and may other things all must be functioning correctly for a healthy relationship. If the equilibrium is out in any area of a relationship there will most likely be problems. Of course, some issues can be fixed by fixing others such as intimacy problems may be fixed by proper communication that kinda stuff.

I have trust and honesty with my platonic friends. I don't have sex with them, however.

In an intimate relationship, trust, honesty, and sex are equal, but it's the sex that distinguishes my intimate relationship from my platonic ones. That is the one person with whom I choose to share my body. (I'm a woman, BTW.)