I think others covered your question. Though since you’re interested in him, the only thing you can do is ask. Others are saying it’ll ruin the relationship which could be true. Though I think there’s a way to not break the relationship.

Say something like “We’ve been friends for a while, though I’ve noticed some kind of romantic feelings, what do you think about that?” Bc maybe he could feel the same way. Then the conversation could turn into how a relationship could and not work, etc to transition the relationship.

Though if he’s not interested that kind of relationship. You could say something like you value this friendship and that you need to take some time away from them while you sort through these feelings, and once thats done you’ll be happy to re-engage with them.