Aries woman and Aquarius man...help!!

I have known this man for more than 15 years. We worked together a long time ago and had a fwb relationship. We lost touch, but about a year ago he found me. He wanted to "hook up", but I decided not to at the time for a number of reasons. We lost touch again. Then, a month ago he contacted me again. This time, I said yes. We've been txt'ing and chatting for about a month, and we are meeting soon. He is so extremely sexy to me, and I cannot wait to meet him. I have always thought of him fondly and as a long lost friend. He is sweet and extremely funny. However, I notice that somedays he just chats all day long. However, on others I can hardly get one word out of him. Considering he sought me out, not once but twice this detachment is confusing to me. At this time, I don't have any emotional attachment to him. However, I could see myself really falling for him if I don't guard my heart. Any advice???