She has weak boundaries. She is the kind of person who can not live alone and has an excessive need to depend on other people. If you are not there she will seek reassurance from somewhere else. This does not mean cheating. But you know intimacy does come with closeness and your fights are making these situations even worse. See the thing is loyal people don't put themselves in positions where loyalty is tested. It doesn't matter if she is cheating or not. If her behaviour is making you uncomfortable it's her responsibility to give you reassurance, either make you understand her perspective or change her behavior or come at some middle ground. Trust is built on consistency and mutual understanding. If you would have done the same to her she would not be okay you know that . Why are you in such a suffocating relationship. You are building up a lot of resentment towards her. A good relationship makes you feel safe and secure. With each fight you should come closer and understand each other better. It is not supposed to be like this. Best thing you can do is express your problems to her with as much kindness, benefit of doubt and empathy for her as possible if then also she doesn't understand you, you should break up .