Desire often follows arousal rather than preceding it
The model everyone was taught had the sequence backwards.
Masters and Johnson described a linear cycle in 1966: desire, arousal, plateau, orgasm, resolution. It became the model taught everywhere, and it left a large number of people — disproportionately women in long relationships — concluding that something was wrong with them because they rarely felt desire before anything had happened.
In 2000 Rosemary Basson proposed a circular model in which many people begin from emotional closeness or willingness rather than spontaneous desire; arousal comes first, and wanting follows it. Both patterns are ordinary. This is now the standard framing in sexual medicine, and it dissolved a diagnosis a great many people had given themselves.