I really wonder what I did wrong?

I sometimes really wonder what I really did wrong and how you can love someone so much but they choose to let you go? It's really heartbreaking having to deal with the same situation day in and day out and always feeling confused about were you stand because one minute he loves you and the next minute your something else. Life is so unfair sometimes, the person you love the most is the one that hurts you the most. I've been running around in circles wondering why we can never get it right? I do all I can to make him see that our life together would be a happy one because he would have all of me and I'd be forever doing what makes him as happy as he makes me.The moment he calls you something else, your heart sinks and leaves you wondering why after all we have shared, he has to be so cold? To tell you he loves you and the next to call you something else. How can someone be so confused or are they just stringing you along, how long is this supposed to last, should you have closed the door or just give him more time because some people are so slow? But have you not given him enough time already? Loving him truly can be so cold and letting him call you something else is just a weakness in the depth of your soul because you can't put your foot down and say, "No I have had enough!"