I’d literally just slowly let it fizzle out by saying something came up, like idk your best friend is going through a tough time and you need to be with her and then don’t text, but if you want to actually communicate I’d say just say you’re not looking for a relationship anymore as the closer you guys got made you realize you need to do some self reflection or exploration or something.
As someone who has been on the other side of this situation, I agree with #1. Let it fizzle out and hopefully he gets the hint. Or just be like, I think I see you more as a friend. I was told I was seen more as a “little sister”. Which yea it’s gonna hurt a little, but it’s much better than being led on.