I don’t know why

My boyfriend ghosted me we have been together one year and now is treating me as I don’t exist he broke up with me that I tried everything to make peace but I am only chasing a person that doesn’t want me. I have been through a lot of breakup even a divorce in the past so I feel completely stupid and ashamed of chasing him and trying everything for a person that doesn’t care about our relationship. I don’t even know what the problem really is I just know that he drastically changed and he has been completely isolated and I am so much hurt