Can loss of nocturnal erections cause desensitation of penis making sex less pleasurable and harder to reach orgasm? Can this condition be improved?

No and yes, The loss of nocturnal erections can not cause desensitization or difficulty in reaching an orgasm. The fact that you have no nocturnal erections, however, may be a symptom of other endocrine or medical problems which decrease libido and sex drive. You need a consult and lab studies with your physician to rule out medical problems. Meds, diabetes, low T and other disorders can cause this. Good luck.