Paladin oaths are all based on subjective things. Players don't necessarily have the same opinon on what constitutes honor, etc. as the developers, and as a matter of fact, the opinion part of oaths goes beyond the meta elements of player and dev and even goes into character opinions.
Minthata's Oath of Vengeance goes from vengeance towards the enemies of Lolth, to enemies of the Absolute, to ultimately followers of the Absolute, all without becoming an Oathbreaker.
It's probably impossible to implement individual opinion on what determines becoming an oathbreaker in a game like this, so instead, it would be best to have any dialogue option that would break a party member's oath be flagged as such, so that we know what the devs had in mind and can act accordingly.
