Tell him your sorry but you don't like him. Go off and cry. Then get over it. You will feel shitty, but you won't make him feel as shitty as he would if you just started avoiding him. Trust me, I know. Directness is sometimes best. It's best to just get it over with.
make a clean break. it's worse to lead the guy on. make it clear that you just aren't feeling it. ask him to please stop being so clingy and respect your decision.
Yes, leading a guy on is the worst. My now ex-girfriend did that to me after us being together for around 6 months. She said she didn't want to hurt me. Not only did it hurt me....alot. It also made my opinion of her drastically change. And I know I wouldn't feel how I do about her now had she just been honest to me about herfeelings when they first changed. Honesty truly is the best policy.
yup... like they said, you should tell him that you dont feel for him that way and stuff... at first he'll probly keep calling you and telling you how much he Loves you , but withen a few days it should die down..