lol... wench
The ideal starting wife seems to be Feona; a good boon if you play mage (or if you just like more powerful spells) or like royal snakes. Then depending on units and god-items you get, Princess Neoka or Xeona are good game-finishing wives.
It goes without saying that you need to de-equip your wife before you divorce her, but the perfect time to divorce her is pre-Elinia, the return trip, since you could splurge on runes and crystals at the dwarf king's son's castle; ideally, you should have less than 100,000 gold before divorce.
Unless you are going for a highest gold run.
I might even be wrong in this, as the record might be tallying all gold, spent or not. That would make the runes/crystals splurge all the more meaningful.