Hello Rick,
In Catholicism, we are not moral relativists. We believe there is an objective moral law. The situation and circumstances do not change the objective part of morality because they are objective. So asking if the situation would make contraception okay ends up sounding like “Ok is this still an evil in this situation?” Yes, it’s always an evil.
NOW, though, there is one thing to consider: moral culpability. The heart of the moral law is charity/love–love of God and love of neighbor. This situation involves a grave reason to avoid pregnancy, meaning avoiding it is a moral mandate. Disregarding the health and wellbeing of mother and baby for the sake of avoiding a particular sin is not what we’re called to do. Hence, the couple is between a rock and a hard place.
Now, abstinence is not immoral, though St. Paul warns us about it. This path may stretch us beyond the virtue we have cultivated in ourselves.
So in this case, sin seems to trap us. We can’t morally risk pregnancy. We can’t contracept. We may be too weak to completely abstain.
In such a case, I’d say the “lesser” sin is a vasectomy. But make no mistake, the lesser of two evils is not a Catholic moral teaching. Avoiding the graver evil does not justify the lesser evil. It remains objectively evil. But considering everything, I would say such an individual has mitigated moral culpability.
I’m sure others would disagree with me because of the amount of deliberate effort one has to put into getting a vasectomy. Sometimes the temptation is to prefer slipping into a greater evil. But avoiding the lesser evil does not justify knowingly slipping into the greater evil either. This fails to recognize the amount of immorality an the gravity of sins the individual is trapped in. There’s a lot of spiritual pride in preferring the route beyond your strength. There is no virtue there.
But ideally, this is something that you shouldn’t seek counsel on the internet or from a friend over. Such an individual should discuss their situation with their priest. In an ideal world, the priest would counsel the penitent to continue to recognize the sin but to humbly accept their limited culpability. The priest would counsel the penitent to encourage anyone else in similar situations to talk to their priest privately rather than causing confusion through a game of telephone where suddenly people start saying “contraception is justified in some cases, says this Catholic priest.” No, not justified. Culpability is mitigated. There’s a difference. In the meantime, people wouldn’t go on forums double checking their priest’s answer to then have a bunch of self-righteous strangers proclaim the priest is a heretic, leaving the person caught up in their own guilt and uncertainty, finding their situation and the lack of mercy they experience from others scandalizes their faith in the Catholic Church.
But we don’t live in a perfect world.
We should pray for our priests and such situations, and pray for the wisdom to know when God wants us to be an instrument of mercy, consoling people in their troubled times. This really isn’t all that different from a poor person stealing out of necessity.
I say again. In an ideal world, you would express sympathy with the individual and advise they talk to their priest, or maybe even advise them to talk to a specific priest you trust. Such a saintly priest would basically council them away from the legalistic thinking that says that the Church doesn’t care for their life and health or the life and health of their children. The priest would identify why the couple feels like the Church’s teaching is saying that and council them on their moral misunderstanding about moral culpability and no one would cause others to second guess the priest’s council.