Why is my ex- partner of 3 yrs., all of a sudden disappeared and now has no communication with me ?

I was in a 3 yr. relationship with a butch up until the point we both were incarcerated together. Then is when I learned she is very promiscuous. She exclaimed time and time again that I have her heart. I forgave her understanding she's 22 and I'm 29 the difference on how he looked at things I can't get mad especially if I accepted the age difference. After 5 months we were released, excited and anxious and just couldn't wait to be with each other. It took another month after we were out but we finally were together again. Nothing was different we loved each other even more. Laughed, played, ate, pleasure and etc. two days she stayed with me. Third day she left with the promise to return. I spoke to her one more time that day and after that it's like she disappeared from this earth. It's one week today. While writing this story today, she calls. Starts to explain off top and very defensive when I cut her off and told her no need for explanation. I'm not the person for conflict so I wanted to keep it peaceful. She hung up and I know that it's the last of this bond, relationship that I thought was a big deal, that we would be together forever. What happened? I never saw it coming I still don't understand there was no fight.