"Consider, for example, the case of a woman who is completely financially and mentally dependant on someone and is forced to have sexual intercourse against her will. Sadly, such cases are not just theory but a bitter reality, witnessed more often than one would imagine."

This is describing a rape or human trafficking scenario, not a fully consensual (but adulterous due to one or more parties being sacramentally married to another) union.

If people in second unions can't give full consent to what they are doing, how is this not describing a rape situation where consent is lacking?