Thank You Dr. MPS Ramani for your valuable comment.
This means if a wife has committed an adultery with her lover and wants to protect her lover, it can easily be done by finding the loopholes.
Husband not giving divorce to wife. Husband 1000kms away from wife. Wife wants to settle down. Wife's all the documents are by her maiden name and she didn't change anything after marriage. Husband and wife living separately since 8 years but husband not willing for divorce.
Now, wife finds some other guy and both are deeply and madly in love. So if they live together they can easily find loopholes in the law by putting this line of section 497 "'if the man knows that she is married to another man or has reason to believe that she is married to another man" and can easily escape section 497 by lover stating that he was unaware that the girl is married as she does not have anything which can prove she is married. In this the wife can also support her lover giving statement like "yes, my lover is not aware of it. I didn't disclosed it to my lover because If I would have been disclosed this then I would be unable to get his love."
Case finished. Adulterer man is escaped and wife cannot be prosecuted under section 497. There is nothing more husband can do on this. Right?