Remarriage of divorced, where adultery doesn't occur until after the divorce?

Question

For convenience, assume that this also applies with the male/female roles reversed:

But I say to you that whoever divorces his wife for any reason except sexual immorality causes her to commit adultery; and whoever marries a woman who is divorced commits adultery.
— Matthew 5:32

How would those denominations that forbid remarriage under these circumstances consider the following situation:

• A chaste (sex only within marriage) couple divorces.
• The one that forced the divorce marries someone else (thereby committing adultery).
• Later, the other wants to marry someone.

Would the second person's re-marriage be allowed, as technically the divorced spouse has committed adultery.

Answer 1

In Catholicism, at least, both second "marriages" are invalid and are adulterous, as the "civil divorce" cannot actually dissolve the original marriage. CCC paragraph 2384 reads:

Divorce is a grave offense against the natural law. It claims to break the contract, to which the spouses freely consented, to live with each other till death. Divorce does injury to the covenant of salvation, of which sacramental marriage is the sign. Contracting a new union, even if it is recognized by civil law, adds to the gravity of the rupture: the remarried spouse is then in a situation of public and permanent adultery:

If a husband, separated from his wife, approaches another woman, he is an adulterer because he makes that woman commit adultery, and the woman who lives with him is an adulteress, because she has drawn another's husband to herself. (St. Basil, Moralia 73,1:PG 31,849-852.)

The spouse who was abandoned may not be guilty of the divorce, but would be guilty of adultery if (s)he entered into a new "marriage" while the errant spouse was still alive. CCC 2386 reads:

It can happen that one of the spouses is the innocent victim of a divorce decreed by civil law; this spouse therefore has not contravened the moral law. There is a considerable difference between a spouse who has sincerely tried to be faithful to the sacrament of marriage and is unjustly abandoned, and one who through his own grave fault destroys a canonically valid marriage.

It may seem "unfair" that the innocent spouse doesn't get to have the "fun" of cheating, but that's like the prodigal son's brother's complaint. It's a mistake to think that the sinner is having some sort of fun that the innocent are left out of. In reality, it's better (for one's own happiness in the long run) to be virtuous even if that means some short term suffering.

In these modern times, a spouse who has been abandoned will often seek an annulment from the Church (a decree of nullity) that claims the original marriage was never valid. With such a decree in hand, he or she can marry again. The issuing of annulments is probably overused, and is often cynically described as "Catholic divorce" because of how carelessly some bishops seem willing to grant them, but that is the state of things today.

Answer 2

In the case you described (given that the first marriage is consummated), the first person to physically unite with someone other than the first spouse commits adultery.

This is expressly allowed as a reason that the other spouse can dissolve the union and lawfully seek another partner.

The spouse who files for divorce, when there has been no adultery, and then goes off and marries someone else, is every bit as much an adulterer as the person who simply goes off and beds someone new without doing the paperwork.