Am I the one that's doing it wrong

What do I do

@warmheartedWalker2409 hi there! thank you for sharing this with the community.

I hear you. It is really frustrating and unfair of him to be saying those things to you and be blaming you for something you did not do. :( It honestly really sounds like there is some miscommunication and misunderstandings going on.
Here are some things I would suggest;

Stay Calm: Try to remain calm and composed, even if your fiancé is upset. Reacting emotionally may escalate the situation.

Open Communication: Talk to your fiancé about his feelings and concerns. Ask him what specific issues he's feeling frustrated about, aside from the burger incident. This will help you understand his perspective better.

Express Your Feelings: Share your feelings and perspective on the situation. Let him know that you didn't eat the burger and that you're not hiding anything. Reinforce your commitment to honesty and transparency in the relationship.

Find a Solution Together: If there are underlying issues contributing to the frustration, discuss them openly and try to find solutions together. This may involve compromises or changes in behavior from both sides.

Set Boundaries: If alcohol is causing problems, consider discussing boundaries related to alcohol consumption and its impact on your relationship. Open communication about expectations can help prevent future misunderstandings.

Give Space if Needed: If the situation becomes heated, it might be helpful to take a break and give each other some space to cool off before revisiting the conversation.

I really hope these suggestions help out as much as possible :)