I needs to be mentioned; once your husband has broken his Vow; you may very well feel you have carte blanche.
Many women feel; “Why should I be faithful and chaste; when he isn’t?”
There are women, decent women, who, feel ‘unmarried’. They go out, they meet others, and behave as unmarried women.
After all, he is out with his gal, why sit home like undumped rubbish?
For many women, having a lover, even if it is casual, even if no emotion is involved, makes them feel whole.
For many, being cheated on destroys their sense of self, and getting a boyfriend restores this.
For example; Mrs. L was devastated when she learned her husband, Prof. L. was having affairs with his students.
She was comforted by the gardener.
A relationship began between them which lasted twenty years. When Prof. L died, she married the Gardener.