Responses
If u look closely the culprit's hair is yellowish or goldish so it wasn't the prince cuz he has red hair.
However it could be only shown in the perspective of the MC. What we see might be what the MC sees too, meaning it isn't really depicted nor gave us hints as to who it could be. He might be seeing the perpetrator having brownish/golden eyes, or brownish hair coz of the lighting, plus he's drunk and bleary. A lot of factors to consider. But one thing's for sure, it's one of the dudes.
The strong hold in culprit for me is the childhood friend or the prince...