I learned in your article on divorce that the only time divorce is permissible is in situations where fornication takes place prior to the consummation of the marriage. But what about the case of a woman who fails to tell her husband about sexual encounters that took place prior to their marriage? Can he divorce her after learning of her deception even though the two have already consummated their marriage?
In the specific situation you described, the husband and wife would still be duly married and therefore may not divorce.
First, the woman in your example committed the sin of fornication before her marriage, not after the marriage. As our article explained, only sexual infidelity after marriage is grounds for divorce and even then only when the married couple has not yet consummated their marriage.
If a couple marries but fails to consummate their marriage for some reason (e.g., a soldier who marries immediately before deploying for battle, etc.), then the couple must remain faithful to their vows. Should one member of the marriage engage in sexual infidelity during this time, that act may be biblical grounds for divorce because the couple had not yet consummated their marriage. In this situation, the Bible permits divorce because a “one-flesh” relationship had not yet been established (see Matthew 5:32 & 19:8).
Obviously, this situation almost never happens in modern society. In our modern society, a couple typically consummates the marriage within hours of the wedding ceremony. With so little time separating the two events, it is virtually impossible today for a Christian to invoke the exception Jesus described in Matthew 5 & 19.
Once consummation takes place in any marriage, that marriage cannot be ended except by the death of a spouse (see Matthew 19:6 and Romans 7). Even though a marriage is formed under false pretenses as in the case you described, nevertheless deception does not invalidate a marriage in the eyes of God according to scripture. Scripture never makes deception or even infidelity prior to marriage grounds for divorce
For example, consider the experience of Jacob, who was deceived into marrying the wrong woman in Genesis 29! Though Jacob was deceived, nevertheless once he had consummated the marriage with Leah his marriage was valid and sealed for life. Jacob could not walk away from his commitment to Leah despite being deceived by Leah's father, Laban.
Therefore in the situation you described, the woman’s fornication prior to marriage was regrettable, but once her marriage was consummated, her prior sexual sin was no longer relevant to the validity of her marriage. The marriage has been formed and must be honored by both parties.