What am I supposed to tell him without messing up?

I have to respectfully disagree with gamereaper’s advice. For a guy the worst thing to deal with is when a girl pretends to like you out of guilt. I know it may seem like you want to spare his feelings but please believe me when I say that being honest is only going to get harder for both of you the more it gets put off.

You are not being selfish. I may have been discouraged/crushed when being turned down in the past but the girls who I remember fondly are the ones who were direct but kind when they went about it. They kept a firm emotional distance which respected that I was feeling vulnerable without trying to get involved and “fix it”. In the end, I only want to be with someone if that is what they want too. He may grumble, get touchy or otherwise act immature (we have all been there) but when someone you are interested in tells you kindly but firmly and consistently that they cannot return your feelings the message will get through.

I have also been on the “turning someone else down” end of things a great deal, especially when I was younger, and I have a very non-confrontational nature which at times had me accidentally leading girls on. It was very difficult to be clear and direct but I knew that if I did not do so at the start things would get messy. Remember that attraction may be influenced by how we think, but in the end it is not a decision who we are most attracted to or feel compatible with. It is nothing to be ashamed of.