More specifically, my focus at this time is to try to understand why, under Wenham's theory; a wife would not be prohibited from remarrying her husband even if she hadn’t married another man.
Al,
Again, I have to plead ignorance as to Wenham's view as to remarriage of a former wife who has NOT remarried. I find nothing in Scripture which would persuade me that such a prohibition exists. Our Lord Christ in the NT makes very clear that there is but one legitimate ground for divorce; adultery. This effectively abrogated both the spiritual covenant of marriage and annulled the physical bond. Further, there is also a real "innocent" party and a "guilty" party in such actions. Of course, by the personal teaching of Christ to Paul, it would seem there is a second ground for divorce; desertion, but I have always understood this desertion to be connected with remarriage or infidelity by and after the unbelieving spouse's departure. The point being, that "for the hardness of heart", these OT divorces based upon whatever reason the man felt was justified were allowed... i.e., Moses was unable to persuade the people to repent of this tradition. However, in the NT having received the proper understanding of the teaching concerning marriage and divorce as the people in the OT
should have understood, a legitimate divorce fully breaks the marriage bond and thus the "innocent party" is free to remarry.
Now, how does this affect the view that a man cannot remarry an ex-wife who has subsequently married after a divorce? This is a sticky question to be sure, but I would like to offer some thoughts for consideration. Does the Scripture DEMAND an innocent party divorce the guilty spouse on the occasion of adultery? No, it ALLOWS the innocent party to divorce the guilty spouse. However, there is room and hope for repentance by the guilty party and thus if the innocent party is given to this end, he/she does no wrong in not suing for divorce. Yet, the adultery has effectively broken the marriage covenant and legally allows the innocent party to divorce and remarry. But, there is clearly no prohibition against the innocent party receiving the guilty (adulterous) party back into the relationship. Is this so much different than a divorced woman remarrying after a divorce and then being received again after a divorce or death of the subsequent husband? The
reason/ground for the divorce is the same, it seems, as a subsequent marriage to another man after a divorce. So, how is one to understand all this?

There is one difference one can see in the matter of the desertion allowance, however. In that situation, the one who deserts is said to be an unbeliever. And, if after the marriage covenant has been abrogated by that desertion (and subsequent adultery or marriage?), a remarriage to this person by the innocent party would be forbidden but on another ground... i.e., a marriage of a believer to an unbeliever (2Cor 6:14ff). Thus there would have to be a major repentance on the part of the guilty party; repentance of the breaking of the marriage bond and repentance toward God and faith in the Lord Christ unto justification.
Okay.... enough of the rambling thoughts. What do you think? You really haven't stated where you stand on this matter of remarrying a former wife who subsequent to a divorce has remarried and then has either been divorced or widowed.