How can I stop dating him without causing drama?

I know this is a typical answer, but it's honestly the only answer: TALK TO HIM! That is honestly the only thing that will work. Tell him how the feelings just aren't there anymore, but you would still like to be friends. Now, don't expect it to be easy. Even if he understands, it will be awkward at first. However, give it time. Before you know it, you guys will be talking just like friends.