The woman doesn't get turned on by any attempt to show him an erection. His dick gives up, thinking it's no use, and starts to flop. But then the woman makes a move. Just as his dick is about to go completely limp, she reaches out her hand and starts stroking it! In fact, she was turned on by the moment she saw his erection! But the conflict in Kokoro creates this time lag, and as a result, he starts to act while his dick is still limp.