What causes a huge problem in any relationship is lack, or wrong approach in communication. Lack of communication, means that both parties barely create time to communicate effectively with each other. Of a truth we all have seen how important communication is, and how a relationship can completely die off because of the lack of it.
One of the things that gets in the way of communication in a relationship is assumptions. That is, when one party believes the other party knows what they are thinking, and expect that party to do for him/her what he/she have not communicated to the party. Instead of saying, "You should have done", "that should have been," "You should have known," etc., you'd better talk about it.
Anything that can prevent communication from a friendship or relationship can disrupt it. There are things that seem good to you and even make sense, but when you understand the other person's point of view, you can start to see things from their point of view and you will realize that what you consider good may not be as you thought.
It would be surprising to learn that so many relationships fall apart, not because of something big or something very serious, but because of something so trivial that could have been fixed with a simple fix. Simple conversation, but one party will wait for the other to start up the conversation and vice versa. Does it really matter who initiates the communication or apologies first?
It is important that in any friendship or relationship you are in, that you have an effective communication, and it is up to both parties to initiate it. However, it doesn't always have to be one-way so it doesn't backfire in the long run.
Now that we've established the fact that communication is essential, it's worth noting that it's not just communication that matters, but how you communicate. Someone might say something and instead of creating positive interactions, it destroys the relationship.
This is why we must be very careful in how we communicate and avoid inappropriate or incorrect use of any communication tools - words, expressions, feelings, etc. You would be surprised that even omitting a letter in a word can change the entire meaning of the entire sentence. Remember the popular joke where a man wanted to thank his neighbor for letting him use his Wi-Fi, he sent me a text:
Thank you for letting me use your wife.
instead of
Thank you for letting me use your wifi.
The first sentence had just a letter typo but it caused a lot of damage and distrust between the man, his wife and his neighbor.
Another thing is the tone of voice and countenance. Certain tones and counternance can have a negative effect on communication and even annoy the parties involved. It is not just about saying something or making a statement, but the tone and emotion behind the statement is just as important and affects the overall meaning of the words.
You must apply the tone and emotion that best conveys the meaning of the word as intended. To guide you in this matter, try thinking that your partner has feelings too and putting yourself in their shoes when communicating.