@girlie,
Just making a guess here, but I'm going to assume he has other options on the side that are in flux so, while he wants to keep you open as an option, he doesn't want to "put all his eggs in one basket" quite yet.
Other possibilities include he's in a relationship already, was testing the waters with you, and wasn't completely sold enough to break off what he already has.
Or he may have guy friends that are giving him **** about dating a 31 year old.
Or (just judging from your posts here) your strong personality was/is a little overwhelming for him and he's just not sure what to do with it.
I'd recommend backing off. Guys definitely don't like to feel forced, so putting any sort of pressure will just shut him down. He will come around or he won't and if you decide you are tired of waiting then gracefully move on.