Maybe this is bad advice, I'll be the first to admit I know little about relationships.
From the perspective of someone on the other side of the friend zone who wanted more, I'm really glad that I asked and was graciously rejected by someone who's become a good friend. We were also spending long days together 1:1, and while it was clearly platonic up until that point that I asked, there was at least in my mind a hope that it could escalate. I've been on dates that were a lot less fun and intimate than what we usually end up doing. Of course it's a bit different since I instigated, but I guess my point is I'm glad that I found out sooner than later. Now we can both enjoy our friend time and I don't have to obsess over little signs and wondering what exactly we're doing. I could have easily seen myself just letting things progress and spending more and more time together without knowing whether I was getting closer to a romantic relationship or not. That would have been mostly my fault, but I still would prefer to know sooner.
It seems like if you're already good friends, talking about something like this could start out awkward but shouldn't end badly. Just explain it like you have here, I don't see anything wrong with that. It could be hilariously awkward because he also doesn't have feelings like that for you, or it could be eye opening for him and allow him to move on.
Of course you don't want to unnecessarily hurt his feelings. I might avoid using words like "never" or "always" etc. The goal is not to let him know you don't find him at all attractive, only that despite doing somewhat relationship-y things together you're not actually looking for a relationship, and you hope that's cool because you love how things are right now, and you just wanted to make sure your friendship didn't blow up because of a dumb misunderstanding. Besides, even if you mean it right now, "never" is a pretty strong word...
...Shit what do I know :D 2 cents I guess. Struck a chord because this is just happening to me :) But +1 for clarity.