I'm going to punish my fiance for not fulfilling a promise
Must have been an extremely important promise if that's necessary to do.
You have to do that sometimes. You have to have consequences when people don't do their best
I think that in this scenario, you should be a bit more forgiving. Being so harsh with someone close to you can strain a relationship.
I don't give a fuck. I'll go full judgmental on her.
I'm sure whatever she did wasn't done maliciously. You may push her away if you try punishing her. You're both adults, so you should just try to talk it over.