Don't assume and don't accuse unless you know it to be fact! You hurt people when you make accusations that are not true! Just because someone else said something or you heard something about another person, doesn't make it true!!!!!
Assumption and lack of communication are the number one relationship killers. We all perceive differently. We've lived different lives. We have different views. Understand that before getting angry at someone for not believing what you believe. Or before getting angry that your gf has your friend's phone number.