His wife is truly unattractive, but then so is he, so I see yuor point. However he isnt going to turn down an attractive woman drawn to his wealth and celebrity.
Huh? I thought the women in question were 'staff members'. IOW's, women who were dependent on Letterman for their jobs. So far, the evidence does not support assuming that these were attractive women drawn to his wealth and celebrity.
We pretty much know that Letterman is petty & vindictive so there's an equally good chance that the conquests in question were yielding in order to avoid getting pink slipped.