aloof, antisocial, cold-eyed, cool, detached, distant, dry, frosty, hard-hearted, indifferent, offish, pitiless, remote, reserved, standoffish, unbending, uncaring, unfeeling

disaffected, unconcerned, uninvolved

cold, frigid, unfriendly

callous, cold-blooded, hard-boiled, heartless, pitiless, ruthless, soulless, unromantic, unsentimental