I'm unhappy in my relationship

I've been with him for 3 years. He never really made my heart flutter, but he's a very nice man. He's actually the kindest boyfriend I've ever had, I've just never really been attracted to him. I just can't gather the courage to break up with him because he's absolutely head over heels for me. I know I'm chicken shit and I'm not looking for advice or criticism because I am fully aware of what I should do, just needed to confess. Thanks.