For adults, there are two strong physical needs vis-a-vis a primary loved one. Tenderness needs, which in psychology are termed oral needs, and sexual needs, which are termed 'genital needs'.
Because of the the near universality of early oral deprivation in our culture, it is common for later sexual activity to become a primary way to receive tenderness, such as gentle touch. The template for satisfying oral needs is breast-feeding (hence the term downward displacement--displacement from breast to genital.) As a child or as an adult, oral need are fulfilled linearly over time. Sexual needs are not linear but are fulfilled by the intensity of the experience. It is in fact healthy (but not necessary) for a sexual encounter to develop quickly and end explosively. Afterwards separating is often desired by both.
But if oral needs are the primary focus of a sexual act, a more explosive encounter is seen as sordid. Sexual aggressiveness and leaving are seen as signs of abandonment. Perhaps this is because in situations such as an affair, sheer necessity of little time together tends to leave out the oral aspect and emphasize the genital or explosive. This is one reason that 'illicit' sex is found more exciting at times. The limitation imposed by downward displacement is that fully-adult sexuality (and satisfaction) is never achieved.
Balance is possible if there are ample opportunities for physical contact that won't lead to sex. If either person is insecure about sexuality and their desireability, this can be experienced as a rejection. Unhurried touching without the possibility of sex is a mainstay of sexual therapy. It alllows sexual feeling to build, and helps disentangle oral from genital.