Even more serious than this case....when I read about Lot's two daughters getting Lot drunk in the cave and slept with Lot and gotten two sons to extend their father's legacy...was that justified ? Lot could have moved to another city and marry another woman and his two daughters would be able to get a normal marriage. In the ancient days a mature woman with no husband was not respected, it seems, and even worse, if no natural children ( especially a son ) of her own. Yes thanks for the reminder that Bible recorded true historical events, both good or bad.
Another situation for widower or husband and wife far apart ...sexual fantancy with one's own wife, either already dead or still alive, I think, would not be deemed sinful, since it is extension of a normal loving husband and wife relationship ? Or, if the wife went astrayed or devorced but the ex-husband still loves her and still fantasize about her ...and if she already remarried or not yet remarried ?