This article covers almost all reasons why couples argue. They are presented in the Guardian. http://www.theguardian.com/lifeandstyle/2015/mar/13/the-top-10-reasons-why-couples-argue

However there are big differences with individual couples on what is and what isn’t said.  Many couples argue over sex without even mentioning the word or discussing sexual issues. Instead, when they are frustrated about having too much or too little sex they complain about trivia such […]