An FWB with potential for MATE

I need advice on how to handle a certain situation. I am a Libra early 40's and I recently became sexually involved with a younger, very mature man(32). However, we work for the same company different departments and have flirted w/each other for over 3yrs, we both acknowledged the chemistry between us but only acted on it once, but it took 3 yrs to do so. I like this guy he has the potential to be something more but we initially stated that we did not want anything serious. But I am confused because I am not sure what that means to him. He calls me baby, sweety, he is very attentive, easy to talk too, etc...I don't want to run him off, but I don't want it to be another 3 yrs before we hook up. How do I approach the matter with him as to what he expects from the friendship/relationship; what are the rules. He can be a little shy, and lack initiative, but I don't want to seem anxious or anything.

Are Libra men always so passionate and caring even in a non committed relationship? It's hard to explain but I know he is feeling me just as much as I am feeling him but doesn't want to be in a relationship for fear of being hurt. I know this from conversation with him. I just don't know how to deal with him or what to expect from him. Can a man give me some insight? I hope I made a little sense here.