Desire lies in the fact of anticipating through imaginary processes a pleasure hoped for in reality. It corresponds to the phase that precedes and accompanies the rise of excitation. Desire troubles can be divided by: an "excess" pathology (hyperactive desire) and a "by default" pathology (hypoactive desire, even sexual aversion). This article discusses the "by default" desire troubles. The lack of sexual desire can be a normal occurrence. It becomes a problem when it lasts too long and is a source of pain and/or conflict within the couple. This problem occurs more frequently with women than it does with men. This can be linked to hormonal differences: testosterone is the desire hormone, while prolactine is the anti-desire hormone. Men seem to be quantitatively more provided with desire hormones than women. Also, women are often subjected to period's hormonal fluctuations. On the psychosexual level, men have a bigger need to actively express their sexuality in order to consolidate their masculinity. Women can more easily rest on feeling the other's desire to be reassured in her femininity. To evaluate a problem of lack in sexual desire, we need to explore five etiological axis: -an organical axis; -social, professional; -familial causes; -relational problems: helping couples in clarifying some concealed conflicts; -interpersonal problems: when there is a need to fetch a psychic internal reality, as the latter stays condensed through erotic imaginary processes (a reflection of someone's true erotic personality). A therapeutic strategy will depend on that kind of assessment and therefore can rely on multiple disciplines.