What exactly does it mean to be someones Valentine?

I met this wonderful guy 13 months ago and have been great friends he is way younger than me and I really wish we could be together. He called me the other night saying he missed me and wants me to be his Valentine. I’m the most excited person in the world. We have never gone out before and he wants to take me to dinner. I told him I would love it! Should I buy him something and any suggestion? Do you think he might kiss me? I’m married and getting a divorce and I think he’s been waiting like a gentleman for me to be divorced. He is the most sweetest guy in the world. No one has ever asked me to be their Valentine before and nothing good ever goes on for me on Valentines day. No suprise flowers or nothing. This is going to be so special for me and him.