It seems clear that since the fall, man lost the ability to love and obey the very God who created all things, including himself. It also seems clear to me that man cannot regain this ability in his own strength.
Man lost the ability to love and obey God when he chose to not love, or at the least when he chose to love something other than God more, and when he chose to not obey God, in choosing to obey something other than God. Is this why his choice was taken away? He'd never be allowed to love nor obey God ever again unless God wills him to? That begs the question, why did God not will man to love and obey Him in the first place? Why are we not born loving and obeying God if that is how Adam was created?
Rather, it seems to me that, in order to 'regain' this ability, God didn't (re)give him the ability to choose but the grace of not counting his wrong choice against him for Christ's sake, that is He honors Christ's gift as worthy to atone for your wrong choices in order to raise you up as a newborn, but not without Christ this time.