Contraception will often be mutually preferred, and reflects no loss of trust in the other - but rather a commonly shared anxiety about future circumstances, deemed best avoided.
The quote from the wedding you provide - and its reference to “faith in each other” seems to stand without reading in an interpretation connected with contraception. I suspect the quote simply assumes that the coming of children “will happen” (like heath, sickness, joy, etc) and thus you accept that unknown future. It’s silent on whether you can influence your future.
I wanted to add something as I see it from another perspective.
Isn’t that the problem though, or one of the things that makes contraception a problem. The feeling of something not being that bad, as both spouses are in the same page (in the case they both consent of course), a kind of false security that relies on each other, which helps move away from the teachings of the church. Doesn’t this acceptance helps us think that contraception might not be a bad thing, or mitigates to some sense the wrong we are doing. I would say that this “trust in each other” relies in what the spouses think might be a good, but in reality is not a good. Like you wrote, fear takes a part in the equation therefore the spouses should always have clear that this consent introduces sin. In the means we see this clearly we will not dare to think contraception is good, and although we might incur in it, we will know that it is because of our weaknesses, and that we will need cleansing after, by confession (1 John 4, 16-19). Therefore we will be clear that we cannot go to communion, as we did something wrong. We need to be clear of our impurity to look for our purification. This is why some might not have a problem and go to communion without thinking they need to go to confession first. Trust is a difficult word, because it implies positive traits, but a trust that is pure will rely in the faith (in Gods traits). This for me is a tainted trust that will not get you walking in the path of God, if one stays in the thinking that this trust (consent) is viable. Exactly this is the problem when we see part of goodness as total goodness. Goodness can’t do evil, love can’t do evil, if it introduces it and doesn’t call it evil, then we are starting to detach from Gods way. That’s why we need to be careful, as something that has some good doesn’t necessarily means that it is good (as it will not keep you in The Way).
The faith in the spouse in marriage takes firstly the consideration that all good can only be obtain through God, that’s why we get married. The sacrament of marriage (this faith that this union is a sacrament) justifies the union between man and woman, therefore this sacrament sanctifies the couple in as much as they follow the faith (and therefore love, as faith is acted through love). The faith in the spouse relies firstly that we will follow the first commandment above everything, as it is the first. This is because trust relies in the protection between the spouses, in the looking out for the welfare of the other (an attribute of love). But the welfare relies in what we personally see as good, but as we know it, only God is good, therefore, in the means we don’t trust God, this trust between us will be tainted, and even if it can have some positive traits, doesn’t mean it will take you in the path of God, or that God wants. This is why even if the consent “doesn’t reflects” a lack of trust in one another, it doesn’t state that the trust is following The Way, which is very important (for our holiness and spirituality), that’s why, we need to see goodness through God (as scripture lets us know).
We know we have weaknesses, but these weaknesses cannot make this situation a way, because The Way is already the one we need to follow, any other way would be part of our original sin or part of our free will deciding not to follow The Way.
There is a scripture I really liked, because it was one that really spoke to me, and told me that morality cannot be followed correctly when we don’t establish where good lies. Mark 10, 17-31 and Matthew 19, 16-30.
Only when good is seen in the “level” of God we will act the goodness that we need to act, the same way as love. That is why it is important that we understand that only God is good, for if not, we can think that good is anything that “appears” to be good. Therefore we will be confused and not see what we need to see. I know that a lot of people know this, but I thought it was important to put it here, just to remind ourselves, that we come from goodness and that’s why we always have some good or can have good “parts” in us and act those partly good traits. But those traits will not make you walk in the good path (Gods path) necessarily, because they can choose not to follow the Principle (God) that makes those good traits actually good.
One that is “rich” (has many “treasures”) should be wary were he puts his security, his trust, his faith, for if he is wrong on that choice, it can cost him a great price. To be able to leave everything is a leap of faith, faith on what we believe matters most.
The beauty of all, is that only in trusting God we will love the way we deserve to be loved, only through God we will give the dignity we deserve. Because only through God we elevate what’s good and what’s love, to true goodness, to true love, but for us to do this we need to surrender and be grateful, to trust that God is the true good, that His way is in fact The Way.
In my case the root of all evil is not trusting God. In not trusting God we decide what is best.