Communication is a huge key in any relationship. You must know how to actively listen and respond to the concerns voiced by the other person It is very common for many to listen to respond instead of listening to understand.
When you are listening to respond you are not actively listening, as your brain is working on what you are going to say next instead of what is actually being said. There is also the natural want to be right which can also be damaging in a relationship.
Effective communicating does not mean you will always agree because you wont. by learning to communicate effectively you will both feel like your individual sides were heard and you can both work out a compromise that allows you both to move forward from the discussion.