Of course it is. How would two people get along together perfectly if they do know know their partner well due to dishonesty?
yes, honesty is a big factor in a relationship but I also believe that respect and love will be as great as honesty. Because when you respect someone you won't have to lie or cheat on them.
if you're need a conservative relation or you live in the heaven...so you have to honest, but now you live in the theatrical-world,stereo tape live, or in camouflage relationship...so we must keep our secrets and no full honest to everybody...don't be naif.