I would think that it would depend on many factors…
How many kids does the couple have already? (If the couple already has 4 or 5 kids, that may change the complexion of the question).
Are there some circumstances that would make having additional children an undo hardship? (mental illness, work issues, health issues, etc).
What is the age of the couple? (The partner may reasonably think that she/he is getting to old to safely care for a child or carry it to term).
Was the number of children discussed before the wedding?
For example, two people in there mid twenties get married after agreeing to have two kids and use ABC to regulate pregancies. One person, after the marriage, then undergoes a conversion experience of some sort and becomes a hardcore Catholic and will not use birth control. That situation is delicate, because the non converting partner still is in the marriage, and their desires must be respected. I could see that ABC would not be a deal breaker there.
Another example: A couple has never practiced ABC, and after 8 years has 6 children. The wife, during the last pregancy developed insert medical condition here which could endanger the fetus in any subsequent pregencies. And lets assume that the wife has significant enough variability in her cycles to make NFP unreliable. I could see that ABC would not be a deal breaker there.