Needs advice!

So I’ve been talking to this guy for three or four weeks now and we get along really well we’ve become friends he’s also very handsome. I’m also very sexually attracted to him but I don’t have any romantic feelings for him and he now he has feelings for me. I don’t know what to do. Because I really don’t want to hurt him but I don’t see us having a relationship and he thinks that I will develop feelings for him but knowing myself I know I won’t. So how do I let him down without really hurting his feelings? Please help