Will my fiancee ever get over his grief?

I have been involved with a man who lost his fiancee 2 years ago to an accident. He found her with head trauma. I know that grieving is hard and his life with her just ended abruptly and I know that no one will take her place. He lead me to believe that he was ready to move on so I opened my heart to him and after we were intimate he came back that he just cant let his heart go. Will he ever find happiness and closure in his heart to love again?