Yeah not like that rules or laws have much meaning for those in power, or want more power. U can't do something in the open, than it's cloak and dagger approach.
There are so many ways Taina could die, without the MC being blameable for anything...
-Like Ully as she poisoned the food/drinks (and here none gave fuck that women have died), would be a shame if someone trys to poisen the MC and they got Taina by accident.
-One of the Soldiers found out, that do to her betreyal, his friends or family died and so he seeks revenge. While he was killed, Taina succumbed to her injuries shortly after.
-An ''ambush'' of bandites/or rebellius slaves
-An assassination attempt on the MC's life, evidence points that it was orchestrated by Fu, Taina died heroically as she took a bullet, which was meant for the MC, in the subsequent firefight all of the assasins were killed.
At the very moving burial, infront the gathered citizens of Nord, the Lord swears, that he will bring Fu to justice...
Not to mention, even without breaking the rule, which she mocks MC about, u could easily make her life so miserable, that death would look like a mercy kill in comparison.