Wiktionary
sexual anorexia
n. A physiological state involving loss of sexual appetite either entirely or episodically based out of an anxiety or other physiological disorder; or by extension a dry spell
Wikipedia
Sexual anorexia
Sexual anorexia is a pathological loss of "appetite" for romantic-sexual interaction, often the result of a fear of intimacy to the point that the person has severe anxiety surrounding sexual activity and emotional aspects (i.e. an intimate relationship).