Communication in relationships is very important. If you don't have communication then you will most likely have fights and the outcome will eventually be a break up.
During relationships two people have two different wants and needs. It is very important early on to discuss those needs. What is it you want out of a relationship? Are you looking for a long term relationship or to just date casually? If you agree on being exclusive then you are in a relationship.
During the relationship the subject of sex may come up. One person may or not be ready. That is very important to communicate. If you ask the person what they want but don't tell them how you feel and just break up with them, that is no communication. It is also mean and immature. When you love someone you accept them as they are and work through your issues. That is communication and that is what communication is all about.
When you are in a relationship communication is a must. Love is also putting the other person's needs before your own. If you think about yourself or push someone to do something that they don't want to do then you shouldn't be in a relationship.