You know, while I understand why you'd want to keep him around, isn't it a bit unfair to do so knowing that he's going to want more from you and probably infer more about your relationship from the time you spend than he should?
While I don't that you have to be fully responsible for other people's feelings and decisions - you do need to be straight up with them in the first place. You like him for what he brings to your life: you get your emotional needs met without doing any of the hard work. But you know there's no way you'd be interested. But flip the situation, if you were in his shoes, wouldn't spending all of this time together make you think that there was more than just friendship given that he knew how you felt? Exactly.
Now consider that you're trying to figure out how to kick him into the Friend-Zone while still getting what you need out of him and well, I'm going to suggest that maybe you stop spending so much time with him and eventually fade him out altogether. You've seen the movies and episodes of The First 48 and Law & Order where these things end badly.
Feelings can't just exist in limbo. They need an outlet. Either they get reciprocated or they get deflated. You have none. He does. I know it's not fair and a bit abrupt but chances are that you can't keep him the way you want without leading him on a little bit.
Of course, if you just tell him there's no way in hell you'd date him and let him decide, then have at it, just realize that might also end badly. But at least you were straight up and honest with him.
You're never obligated to have romantic feelings for male friends just because they like you and are nice to you. If you've never expressed romantic interest in him, then that's all you really need to do. Continuing a friendship with him does not mean leading him on! The sad reality is that most guys like this eventually expect something in return from women, and when they don't get it they get pissed and complain about being friend-zoned. But in that case, he's just a crappy friend and that's on him.
Well there's that, but there's also that if you spend lots of time with someone who has feelings for you, those feelings will probably just grow and the person will get sad. So not constantly dangling something he can't get in front of him may the kindest option, for his sake.
Sure she could just be all 'you have unrequited feelings for me, suck it up', but they're friends so she clearly wants to act with some sensitivity.
Great answer! I have been in your shoes girl and had many guy friends who expressed interest and I was not interested in anything romantic with them. I have lost a few friends, but at the same time 2 of my best friends are guys that I was honest with and they have come to terms with the fact that anything romantic with me is off the table. We still talk and hang out. albeit not EVERY day but often enough, and the pressure is off because everything is in the open. HONESTY IS THE BEST POLICY. I am not saying tell them that you are not physically attracted to them that might just be mean just say "Hey I really value your friendship but I could never see us as anything more than that."