Why does in a relationship some feel not contented?

when i am feeling discontented in a relationship it is usually because of a lack of communication. either i feel i'm not being communicated to or i feel like i can't communicate clearly to my partner. when the communication barrier is broken and all is cleared up we usually are no longer discontented. if we are still discontented i would think someone was not being honest and the relationship is probably ready to be over. i believe you need three things for a good relationship-trust, honesty and good communication. without those you have no reason to be a in a relationship. if you add a good intimate relationship then you have a great relationship!! good luck!