$$S1$$   This inevitable disappointment of erotic lovers means that they rarely remain in a relationship for long. 
$$S2$$   However, because erotic lovers often have an idealized image of beauty that is unattainable in reality, they are especially sensitive to the physical imperfections of their lover. 
$$S3$$   Instead, they go off in search of another, more ―perfect‖ lover. 
$$S4$$   They are easily disappointed by a nose that is too big, a complexion that is too blemished, or a figure that is a bit too full. 
$$S5$$   In fact, erotic lovers strive to understand their lover as fully as possible. 
$$S6$$   Erotic lovers, like Narcissus, who fell in love with the beauty of his own image, focus solely on beauty and physical attractiveness.

 

Which sentence comes second?