Fighting with boyfriend regarding commitment

Hi, Brooke! My boyfriend and I have been together for 4 years, we have been living together for 3 years. Recently we started fighting alot with me questioning our relationship. The most frequent topic of the fight is his commitment, i.e. us getting married and having a family. He does not want to get married – he was married twice already, he also stated that our fights put him in a position where he is not sure he wants to make this important step because it will tie him up. I always dreamed of being married and having a family. I do not want to quit the relationship, I want to work it out but there is something standing between us now. Sometimes anxiety gets the best of me and I tell him “that’s it; I am done” and I leave for a few days to stay with my friend. It’s a constant struggle, back and forth, I am angry and frustrated and I do not want to be this way. I really do not like being like this. What do I do?