Most Helpful Girl
he may have some skeletons in his closet that he can't reveal to you.
or he loves you but has a real huge inferiority complex. he will think he cannot keep you happy, because he cannot take the responsibility.
or he liked you, but could not love you cos he's scared of commitments.
or he's lying and you were just a convenience/obligation. and he's smooth talking his guilt.
or he fell for someone else and couldn't get out of it. or felt he betrayed you and can't forgive himself.
solution to all: move on.