Well, then, they're totally screwed by your theology because there's no way of getting out of that condition.
Jesus said that if you look at a woman to lust after her in your heart, you've committed adultery with her already. That's no different in principle, because divorce also causes people to commit adultery.
This is what the works based religion of Catholicism will get you. Hell with no mercy from God.
FWIW, please provide Scripture verses to show where God distinguishes between mortal sin and venial sin.
Protestants teach that everyone should read the Bible and interpret it for himself. As a result, they do not even agree within their own ranks as to just what is to be believed.
The truth is there is no such religion as Protestant, as each "Protestant" is just one person making up their own religion as they go along, they're all winging it, to themselves they are more infallible than a pope, they are their own god.
No point in discussing anything about the true Faith with a Protestant. If I were to correct the misunderstanding in ONE person for ONE question of life, there would still be millions of other errors to deal with in that ONE person.
Ones Protestants beliefs are unique to him, as Protestantism has no beliefs that require adherence, each Protestant basically invents his own church of one. That is not the case with Catholics. The Catholic Church has doctrines that are unchangeable, and a Catholic MUST believe them, or he is not a Catholic. PERIOD.
A Protestant can call themselves a Christian in a state of grace with a direct line to the Holy Ghost, even if they don't believe Christ is God.
A Catholic is a heretic if he denies one dogma. A Catholic who dies with one mortal sin (heresy is a mortal sin) goes to hell.
Protestantism is like a body care system that teaches that one must eat and exercise to live better. But they leave it up to the person to figure out the rest.
Catholicism is like a body care system that tells you that you must eat good food, what foods to eat, and in what quantities, and what foods MUST NEVER be eaten. It says that you must exercise, how much to exercise, and exactly what exercises to do, and which you MUST never do. And if you don't follow the most important teachings which are vital to your survival, you are no longer a Catholic.
Actually, that one is pretty basic, and was accepted by all of Christianity for 1500 years:
"If anyone sees his brother sinning, if the sin is not deadly, he should pray to God and he will give him life. This is only for those whose sin is not deadly. There is such a thing as deadly sin, about which I do not say that you should pray.
"All wrongdoing is sin, but there is sin that is not deadly.
For instance, St. Paul in Galatians (5:19-21) asserted, "It is obvious what proceeds from the flesh: lewd conduct, impurity, licentiousness, idolatry, sorcery, hostilities, bickering, jealousy, outbursts of rage, selfish rivalries, dissensions, factions, envy, drunkenness, orgies and the like. I warn you, as I have warned you before: those who do such things will not inherit the kingdom of God!" (Cf. Rom 1:28-32; 1 Cor 6:9-10; Eph 4:3-8) Therefore, sacred Scripture explicitly identifies certain sins which kill the grace of God in our soul and deprive a person of eternal salvation.