Legalism isn't a matter of NT/OT it's a matter of what spirit in which you apply the scriptures be they found in the OT or the NT
Nobody is saying you need to run to the divorce court immediately someone fails to provide make you happy or even commit adultery that is NOT the point and has never been
With everyone of my comments there is an implicit assumption of good faith and long suffering and a true willingness to make the marriage work on the part of the aggrieved party . The final Line being crossed only when it reaches a level of pressure that the individual in question cannot bear and that's firmly between the individual and the Lord not bible thumping legalists
To continue to insist that the only two applicable scenarios worthy of divorce are those that Quest has hung her coat on is what I would consider legalism