According to Osho, sex and death are two poles of the same process. Because birth arises from sex, death is built into sexual life; without sex, as in amoeba’s division, there is no death. Traditions chasing immortality thus repress sex. Existentially, deep orgasm is a brief death of the ego—control drops, the non-voluntary takes over—revealing why both remain taboo and feared.
Sex starts life, so an ending is built in; in real sex your ‘me’ disappears for a moment like a tiny death, which is why we fear and hide both.