How do I let him down gently?

I have a close friend who recently admitted to having feelings for me. I was surprised because he had never said anything about this in the past, so I didn’t know how to react. I asked him for some time to think about it and he agreed, but I can’t wrap my head around it and don’t know what to say to him. I am fond of him because we have known each other for years, but to suddenly try and have romantic feelings for him seems strange and I don’t think I can. I want to tell him the truth without causing him any pain, and don’t want this to affect our friendship in any way. How do I get him to understand where I’m coming from without this damaging our bond?
This depends upon how mature your friend is, because there is no other way of saying this. It’s hard to generalise and say that men struggle with rejection, but you should speak to your female friends or look at past experiences to get an idea of how this may go. The best thing to do is be honest about where you stand, why this friendship is important, and why you don’t want to make things awkward between you two. If he values this as much as you do, there really shouldn’t be anything to worry about. At best, it may take him a while to get used to the idea, so consider giving him time and then reaching out.

What can I tell my girlfriend about my relationship plans?
She wants to know if this is a longer commitment, but we have only been together for six months and I have yet to understand where this is going or how strongly I feel about it. I get the feeling she is reconsidering it if I tell her I need time to sort out my feelings. If you need time, there is nothing to be done about it. If she can’t wait, that is her choice.