Perhaps the most frequent issue with communication in a relationship is the "hard start up".  This occurs when one person has been thinking about what they want to say all day and as soon as they see their partner they deliver the conclusion of the conversation that has been transpiring in their thoughts all day.  The most common reaction in their partner will be defensiveness which pushes the anxiety level in the room to the top.  The confusion about what is happening will lead to an argument because they have not communicated.  The partner who has been thinking about what they want to say delivers the information without the benefit of what they were thinking; just the conclusion.  Imagine how often this happens in your everyday conversation and think about how you feel when it happens to you.  Isn't your first response to become defensive followed quickly by a series of excuses or self-justifying statements?  We all have the ability to justify anything that happens in our favor.  This cycle of communication in a relationship will start to chip away at your friendship as someone is always feeling criticized and somehow doing something wrong.  The communication pattern produces a sense of failure and futility in your conversations which often you will feel yourself pulling away.  Some researchers call this process stonewalling and/or turning away from each other.  Gradually this turning away will lead to subjects becoming off limits for discussion.  When this pattern starts the partners are moving toward living their own parallel lives in a relationship.  As this pattern deepens one feels more and more isolated and lonely without the support of their partner.  It can lead to a sense of frustration about the relationship and eventually create a vulnerability that the person will seek to fill either with higher levels of conflict or they will look outside the relationship to find that support. 

Remember no one is ever able to change a behavior until they can catch themselves actually displaying the pattern.  If you want to effect a change, one first needs to look at how they are communicating with their partner before telling your partner that they are doing it wrong.  You will only increase the space between the two of you by trying to tell your partner what is wrong with them without working on your issue first.  Once you can catch yourself in the pattern, you will be able to stop talking and begin to communicate.  Please try not to forget that just because you thought it doesn't make it so in reality.  You will need to give your partner the opportunity to hear what you have been thinking before expecting a response.  If you learn to communicate how you have arrived at the conclusion you have then at least the other person can know how you got there and better understand what is being said. If you are willing to be more open in your communication you will create a more respectful interaction and help to reduce the conflict in the relationship.  Some communication will be stressful and will require some thought about how you want to present what you are trying to say.  Disagreements are going to be present in the relationship but those disagreements do not have to lead to harming your friendship.