I don't know if my boyfriend is trying to end our relationship or what message he is trying to send me?

I have tried to call him many times and he never returns my calls and I don't know why. My Brother got married on July 4, 2009 and my boyfriend was supposed to be their but he never showed up, He told me that he did not know where the wedding was at and i Know that I told him. he never wants to hang out with me and he is either working or doing his stupid lawn mower derby stuff. His birthday is on Friday August 7 and i don't know weather to call him and see if he wants to do something for his birthday or if I should just end the relationship. One of my friends told me that he is trying to send me a message threw his actions that he wants to end our relationship. I really love him and I don't want to see an end to our relationship after we have been together for 15 months. I just don't know where to turn or what to do. This is the first guy that I have dated for more than 3 months and I really thought that we where going to be together for a lot longer than 15 months. He gave me a promise ring for christmas in 2008 and he told me that if he ever wanted to end our relationship I would no because he would ask for the promise ring back. I just need some answers what can I do to help save this relationship.I know it was ment to be and ever one that I talk to that know both of us said that we make a great couple and that we were ment to be together I agreed with them at the time but know I might be regreating that I agreed with them. What should I do? I am in love but I don't know if my man is in love anymore.