EasterJoy stated “Infidelity within a perfectly valid marriage is not cause for a decree of nullity”
No offence and I know that some may disagree with me on this but:
God’s law: Thou shall not Commit Adultery - is just that a Law and no one should be allowed to diminish God’s laws, any of them.
Jesus reinforced all of God’s laws – explaining that the 2 greatest of the commandments were to Love God and each other as ourselves. To Forgive also, but that does not mean we should over look God’s Laws. As in Matthew 19.9 “that if a man divorces his wife, except for adultery, and marries another he himself commits adultery.”
I view it that “man” can be substituted for “spouse”.
Winter
He also made the rule that what the Apostles held bound on earth would be held bound in Heaven, too. Having said that, in a case such as described, yes, it is quite possible that the infidelity and the invalidity sprang from the same root. In any case, a decree of nullity often (but not always) leaves those who attempted the marriage free to attempt marriage again with someone else. The important point is that
a marriage that began as a valid marriage remains a valid marriage, even if there is infidelity after the fact.
Although a tribunal can find that infidelity after the fact was evidence of bad faith or incapacity at the time of the vows, that is by no means automatic. Canon law list the rights of a spouse wronged by infidelity under Separation with the Bond Remaining, not under impediments to marriage:
*Art. 2.
SEPARATION WITH THE BOND REMAINING
Can. 1151 Spouses have the duty and right to preserve conjugal living unless a legitimate cause excuses them.
Can. 1152 §1. Although it is earnestly recommended that a spouse, moved by Christian charity and concerned for the good of the family, not refuse forgiveness to an adulterous partner and not disrupt conjugal life, nevertheless, if the spouse did not condone the fault of the other expressly or tacitly, the spouse has the right to sever conjugal living unless the spouse consented to the adultery, gave cause for it, or also committed adultery.
§2. Tacit condonation exists if the innocent spouse has had marital relations voluntarily with the other spouse after having become certain of the adultery. It is presumed, moreover, if the spouse observed conjugal living for six months and did not make recourse to the ecclesiastical or civil authority.
§3. If the innocent spouse has severed conjugal living voluntarily, the spouse is to introduce a cause for separation within six months to the competent ecclesiastical authority which, after having investigated all the circumstances, is to consider carefully whether the innocent spouse can be moved to forgive the fault and not to prolong the separation permanently.
Can. 1153 §1. If either of the spouses causes grave mental or physical danger to the other spouse or to the offspring or otherwise renders common life too difficult, that spouse gives the other a legitimate cause for leaving, either by decree of the local ordinary or even on his or her own authority if there is danger in delay.
§2. In all cases, when the cause for the separation ceases, conjugal living must be restored unless ecclesiastical authority has established otherwise.
Can. 1154 After the separation of the spouses has taken place, the adequate support and education of the children must always be suitably provided.
Can. 1155 The innocent spouse laudably can readmit the other spouse to conjugal life; in this case the innocent spouse renounces the right to separate.*
In the theoretical case that is the topic of this thread, however, the marriage was in fact invalid. It is not the business of the General Public of the Faithful to be told why, so we can’t know unless one of the parties involved chooses to disclose that. What we do know is that a valid marriage is not made invalid by the sin of one of the spouses. Their sin can make the common conjugal life impossible (and therefore not morally required), and in that sense of course the sin can “ruin” a marriage, but that sin does not
dissolve a valid marriage after the fact.