When dating him and he’s pursuing you and you’re not interested, then you are the one holding all the cards. You always hear women talking about how they want the guy that is not available, so if you’re not into it just be upfront with him about it.
You have to be firm but kind and just say, “I’m flattered that you’re so interested in me, but I think I am looking for something different”. Men hear what they want to hear, so you need to make it very clear that you are not interested in a romantic relationship with him. Let him down gently; if he’s still a terrific guy then make sure he knows it and tell him you’ll keep him in mind for any of your single friends.
Once you’ve gotten it over with, shoot him an email offering to set him up with one of your friends. If you’ve handled the situation correctly, he may offer you the same. The point is, if he’s a nice person, try and keep the lines of communication open with him – because you never know, you may change your mind. I see couples all the time where it wasn’t love at first site, but got together somewhere down the road. Just remember, it never hurts to go out with a guy even if he’s not “the one”. You don’t know who is right for you until you meet him and give him a chance.