I Am In Love and He Loves Me Too

I don't know if this is the case for everyone but with me, being in love is a happy and sad feeling at the same time. I feel like my heart has been breaking ever since I let him in a year ago. He's the sweetest guy ever too. He's always good to me, supports me, goofs around with me, etc. Maybe it is just the thought of "this is so beautiful, I never want this love to end, but it could, the future is limitless..." and I think that's where the pain and fear is stemming from.