You open up quicker, it takes him longer. I sense he may have trust issues or a fear of rejection/abandonment. I think that may be a reason why he is afraid to get flirty. Do you like him? Stick around, maybe temper your eagerness for a bit and take things at his pace. Easier said than done, but if you feel you want someone more receptive to you, it's your life. You can move on.

Maybe ask in therapy why you are attracted to men that are emotionally unavailable?