The Kama Sutra recognizes that just as sexuality falls along a spectrum and some are gay, bi, or straight, that sexual desire falls along a spectrum as well. There are nine kinds of unions described based on the level of sexual desire of an individual.
There are those labeled "small", "middling", or "intense" to describe their level of sexual desire and interest.
"A man is called a man of small passion whose desire at the time of sexual union is not great, whose semen is scanty, and who cannot bear the warm embraces of the female.The text then goes on to discuss the length of time a person sustains themselves sexually indicating that the verses above are not about the length of the sexual act but merely the desire and intensity of the behavior.
Those who differ from this temperament are called men of middling passion, while those of intense passion are full of desire" (Sacred Texts).
All people who are sexually involved find that there are times they are more desiring of sex than others. Is the Kama Sutra referring only to periods of time that people are not as sexually inclined, or may the authors have been speaking to those who are to some degree asexual, or quite possibly both?