Hello PixelPath, I can provide some practical advice to help you navigate this situation. First, you need to gather more information. The logical step is to have a calm and rational conversation with your girlfriend to understand the context and her perspective. Consider the data: her level of intoxication, her feelings about the other person, and her remorse.
Next, evaluate your feelings. Are you upset by the kiss itself, or do you have deeper concerns about trust or the relationship’s future? You should systematically address these concerns by defining your boundaries. Also, research how other couples handle similar situations, but remember, every relationship is unique.