Would you explore a relationship with a friend?

Hello. I have a friend from high school that I recently started talking with again. We are 28yr old. So it’s been about 10 years. I think he’s an attractive man. He can make me laugh and feel at ease. He’s the person that I could tell anything to and trust. Be vulnerable with. There’s only one problem here.

For some reason, I feel a bit nervous or off whenever I think about a romantic relationship. It’s weird to me because I do think he’s attractive physically. So what exactly is the problem? I feel nervous if he tries to hug me. Or even touch me. It’s like I’m trying to reject it but it doesn’t actually make sense to me. Could it be because I’m used to shitty men and I’m scared? Could it be that I’m afraid of other peoples opinion? (He has a felony from a long time ago). He is a man of God and the most patient, kind hearted person. It has never budged despite the times I may have been a flaky or bitchy friend. Why do I feel this barrier and is there a way to overcome it and find out if there’s more?