Even when a remarriage does involve adultery, the adultery relates to the initiating act and not to the state. In some cases, remarriage does not involve adultery. God can, in fact, lead believers into second marriages which are totally free of that stigma.
We see a parallel in the commandment, "You shall not kill." Taking another human life is wrong, and the murderer is to be punished. Yet the law makes provision for one who kills another accidentally, and in war killing is legitimate. Certainly this falls short of God’s ideal of the way in which people are to live together. Yet because of the impact of sin on society, situations do arise in which taking life is legitimate and free from the stigma of murder.