"If a couple does use a natural means of postponing conception, then they still accept each other completely, including their fertility. And they still love one another with a life giving love, there is nothing different between the love expressed between them then, and when a child is created. That's why contraception is intrinsically evil. It's not because a baby is not conceived"
I'm trying to apply this rule to difficult situations where "natural means" doesn't work.
In that case the couple must resort to celibacy.
This isn't accepting one another's fertility at all - it is rejecting it totally along with the unitive aspect of sex.
Common sense tells me this is more damaging to a marriage than resorting to contraception (non-abortificant of course)
In a case as you describe, I would argue that it is accepting each other's fertility completly, and not rejecting any part of them. Yes, abstience is the only moral option, and it is an enormous cross, but it isn't rejecting the unifying aspect of sex, it is respecting it to the highest degree. Rather than polute it in anyway, the couple together unites their sacrifice together.
I have only a slight idea of how hard this is, as a friend of mine has to live this way. It is a tremendous cross.