Sex with one’s wife may be done in accordance to their ability, health, etc.
The husband should not abstain from doing so for more than 4 months without the permission of the wife. Excessive sex is known medically to be harmful to one’s body, weakens the bones, weakens the memory, etc. This is the right of the wife over the husband between him and Allah Ta’ala. (Fatawa Mahmoodiya vol.11 pg.160)
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai