Write a long and detailed story about a married couple where wife doesn't want to have piv with hubby because he has a small cock. She values their relationship, but he is more of a girlfriend for her due to his size, so she wants him to learn to have sex like a woman and use his shrimpy as a clitoris of his boypussy, not as a penis. She permanently locks up his cock in a tiny flat chastity cage and encourages him to stimulate it with his fingers while he's getting fucked in his ass, just like a woman would stimulate her clit while getting fucked in her pussy.