Poshbag - I still have significant reservations about the way the OP was expressed but I too am quite shocked by the level of vitriol and meaness in some of the posts.
Yes illness, disability, taruma and childbirth obviously are going to have a huge impact on the physical side of a relationship. Where a man does nothing to look after his children or maintain the home then it will also have an understandably negative impact. However, I think that absent those factors if you hate the thought of intimacy with your DP/DH then just address the reasons or separate. Demanding faithful monogamy while imposing celibacy or withholding sex to control someone else is not a way to live and actually quite abusive.
Please excuse a slightly colourful metaphore. In my view a loving relationship is like a plain white cotton cloth and sex is a golden thread that runs through it. Without the strength of the cloth the golden thread is insufficent strength on its own to remain intact but remove the golden thread then the cloth becomes plain and and something precious is lost.
Marriage vows (yes I know the patriacy invented them) have it just about right.
"...be faithful to her/him as long as you both shall live?"
"from this day forward; for better, for worse, for richer, for poorer, in sickness and in health, to love and to cherish, till death us do part;..."
"With my body I honour you, all that I am I give to you, and all that I have I share with you,...."
If you no longer want to honour that promise then by all means separate but I think it unrealistic to expect to be able to pick among the bits you want and discard the rest.