Simply replace the unfilled areas such as "" and "[date]" with your information.
Dear [first name],
The reason that I have such a hard time saying that I love you is not because I don't love you. It's just that one of my greatest fears has always been commitment.
I've always ran away in the past when it came to this point. But I have very deep feelings for you and am asking for you help in facing this fear of mine. This fear is from being hurt in past relationships. I always feel like fleeing before I get too closed and attached to somebody.
I love you more than I have ever loved before. I enjoy nothing more than spending time with you and want to see our relationship blossom.
Thank you for your understanding.