Is it worth it trying to date a best friend of 8 years?

Dominique and I have been best friends since freshman year of high school. We immediately knew we had an attraction for each other. He had a girlfriend and I was his best friend, we kissed , we hung out and I mooned after him all 4 years. Finally senior year I was fed up being the other girl (mind you virgin entire time) I stopped talking to him. Our families tried to get us to talk again to no avail. The summer after graduation he finally came around and asked me to be his girlfriend and how I was always there for him. I said no and decided to date another guy. He didn't take that well and decided we couldn't be friends anymore.

Fast forward 2 years we are 20 &19. He has since joined the military and it was like we never separated. He was newly in and was feeling lonely and reached out to me again after not talking for years. He decides that he wants to marry me and wants to start a life together. I accept thinking he realizes that what he had all along and really wants to give it a shot. He gets shipped overseas and I believe he went through something traumatic and shut down on everyone including his family.

Six months later he contacts me again trying to apologize and I would have none of it. I told him I was so hurt and looked dumb picking out wedding dresses and everything to be blown off again and told him to stop contacting me. I blocked him on Facebook and from my phone.

Fast forward 2 more years (22 and 23 years old) and he hits me up on Facebook asking to meet because he is on leave and in town. I go over to his house and its pretty awkward between us. We make small talk and agree to keep in touch since he leaves in 3 days. He texts me later that night saying I was still attractive and glad I gave him a chance. He invites me to come stay with him in May for a week. I agree but later we have to cancel since he is getting deployed over seas again.

Now its August and I will be going to Fort Sill for my brothers graduation ceremony from Army basic training. Dominique invites me to stay with him a couple days since I will be out his way anyway and says he really wants me to see him. He wont have complete free time with me because of work commitments. We know the attraction is there and he has made all these efforts to get me in his life. He also wants to talk about why he shut down after proposing.

Why would he keep insisting me to be apart of his life?

Would it be wrong if we slept together or do you think that would tell me what he really wants?

Is this just him trying to clear his guilt or something?