Marriage is a covenant, if the covenant is broken then the covenant is no longer in effect. The covenant can only be as strong as the covenant makers. That is why God alone can make an unbreakable covenant.
If the covenant is broken and the covenant makers both forgive and go on then the covenant is still in effect. But if one or the other refuses to renew the covenant then now it is of no effect and is of no power.
That is why a covenant breaker is listed in
Romans 1. The sin is not divorce, the sin is covenant breaking. Divorce is the fruit of the sin.
But if someone repents of covenant breaking then what? Do they go back to the first or even wait for them? But what if the first does not want to reconcile?
Many of the no remarriage proponents are living under a law mandate versus the grace mandate. If you are going to do that then you must also use the same punishment for adultery that they used, death. But, that is not available, thank goodness, so today we have Grace.