Hi
There are many qualities that are important for a good relationship, be it friendship, spouse, siblings or any other.
Four important of these are:
Mutual respect:
Respect not just means that we pay attention to them and their instructions on face, but respect means we should value each other's will and the boundaries set by them.
Trust:
Trust is such a thing which increases the more you have it and the more you get. It means that we should place trust on each of our relation that they will not think bad for us and even if we hear someone saying that our friend was saying bad about us, we should have the trust that they will not and do not need to jump at the conclusion.
Honesty:
All relationship should be pure, honest and right from the heart. There should be much compassion and love for each other that we will always be honest in our relationship and wont take the assistance of lies to hide small mishaps.
Compromise:
Sometimes things do not go exactly in a relationship the way we want it, at those times we need show compromise instead of giving up on situations and relationships. This comes from a positive and loving attitude towards our relations.
Hope it helps!