What you are going through is one of the most painful things that can happen to a person. It is natural for you to be terribly sad. I'm glad you have a friend to be with. Sometimes people change and don't even know why they change. Whatever is going on is not your fault. It may not be anyone's fault. It's just difficult and sad. I'm sure there is a forum on this site that addresses the very thing you are going through. You'll find lots of support here. We all care about each other a lot. Join the group and we will get through this together.