DE can be due to the injury to pelvic nerves responsible for orgasm from trauma as a result of pelvic surgery (viz., prostate surgery including  transurethral resection of prostate and bladder neck incision, proctocolectomy, bilateral sympathectomy, abdominal aortic aneurysmectomy, para-aortic lymphadenectomy etc.). Some men report a lack of sensation in the nerves of the glans penis, which may or may not be related to external factors, including a history of circumcision. Endocrine (hypogonadism, pituitary disorders such as hyperprolactinaemia and Cushings disease, thyroid disorders, etc.). Although low testosterone level had been considered a risk factor in the past, more recent studies have not confirmed any association between ejaculation times and serum testosterone levels. Delayed ejaculation is a possible side effect of alcohol  and certain medications, including antipsychotics, antidepressants including selective serotonin reuptake inhibitors (SSRIs), opiates such as morphine or oxycodone, many benzodiazepines such as Valium or Xanax, and certain antihypertensives including thiazide diuretics, alpha-adrenergic blockers and ganglion blockers. Although they may increase sexual desire, stimulants such as amphetamines and cocaine have an inhibitory effect on ejaculation, and can cause erectile dysfunction and reduced penile sensitivity via their vasoconstrictive effects. Psychological (acute psychological distress, relationship distress, psychosexual skill deficit, disconnect between arousal and sexual situations, masturbation style and frequency, etc.) Psychological and lifestyle factors have been discussed as potential contributors, including insufficient sleep, distraction due to worry, distraction from the environment, anxiety about pleasing their partner and anxiety about relationship problems. Idiosyncratic masturbation and lack of desire for stimuli are also proposed risk factors for DE.
As a result, VIP induces an increase in vaginal blood flow accompanied by an increase in vaginal lubrication. The findings suggest that VIP may participate in the control of the local physiological changes observed during sexual arousal: genital vasodilation and increase in vaginal lubrication. Vaginal dryness
Insufficient lubrication or vaginal dryness can cause dyspareunia, which is a type of sexual pain disorder. While vaginal dryness is considered an indicator for sexual arousal disorder, vaginal dryness may also result from insufficient excitement and stimulation or from hormonal changes caused by menopause (potentially causing atrophic vaginitis), pregnancy, or breast-feeding. Irritation from contraceptive creams and foams can also cause dryness, as can fear and anxiety about sexual intimacy. Vaginal dryness can also be a symptom of Sjögren syndrome (SS), a chronic autoimmune disorder in which the body destroys moisture-producing glands. Certain medications, including some over-the-counter antihistamines, as well as life events such as pregnancy, lactation, menopause, aging or diseases such as diabetes, will inhibit lubrication. Medicines with anticholinergic or sympathomimetic effects will dry out the mucosal or "wet" tissues of the vagina. Such medicines include many common drugs for allergenic, cardiovascular, psychiatric, and other medical conditions. Oral contraceptives may also increase or decrease vaginal lubrication. Older women produce less vaginal lubrication and reduced estrogen levels may be associated with increased vaginal dryness. Artificial lubricants
When a woman is experiencing vaginal dryness before sexual activity, sexual intercourse may be uncomfortable or painful for her.