I've been hearing this a lot recently (paraphrasing here):
"I like him and I think he likes me. We're really close friends, but I don't want to ruin or change our friendship in case anything happens."
Y'all are stupid.
If you both like each other, your relationship has already changed and it will never be the same again.
If you don't go for it, an underlying tension is always going to be there. There will be longing. There will be jealousy. There will be awkwardness.
If it doesn't work out, work it out with each other and communicate why you're better as friends--but keep in mind that you probably won't be for awhile until any residual feelings have faded from either end. When that time comes (and it will), it'll be ok.
*Provided you weren't a dick about breaking up, it'll be ok.