Not In A Relationship?

My boyfriend told another girl that he and I weren't in a relationship anymore, even though we were and still are. I asked him why he said it and he said it's "because sometimes it feels like we aren't because we fight all the time." What does this mean? I want him to be able to talk to me about how he is feeling, especially when it's something like him feeling that we aren't even in a relationship anymore. How can I get him to be more open with me about his feelings and not talk to other girls about it?