When it comes to dating, how do you usually offer rejection?

I usually try to be as gentle as I can about it. The last time I just told him, that I think he is a really nice guy; but we are just not right for each other. And I”m sure he’ll meet someone just right for him.

In truth however I felt he was rushing into things way to much. He told me that he cannot stop thinking about me, after only one date.