WIBTA if I didn’t pay my friend back for ice cream that he bought me?

For context, I was at a get together at my friend’s house when my friend and a few other people decided to leave the house for a bit to get ice cream nearby. While they were gone, my friend and his girlfriend called me to convince me that I should pay for a "surprise" ice cream flavor that they said would be a treat representative of my favorite movie (this will be important later). Just to be clear, I would be paying my friend in this case for the surprise ice cream that he bought for me, which already seemed a bit dubious in my eyes. However, he and his girlfriend eventually convinced me, and since I didn’t have any money on me at the time, I promised him verbally that I’d pay him back the $8.00 USD or so the ice cream would cost him at a later date.

When he got back, the ice cream he brought me was yellow and Nutter Butter flavored or something similar. I was somewhat disappointed by this and asked my friend how this flavor at all related to my favorite movie, to which he confidently told me that my favorite movie was Despicable Me and the yellow flavor was representative of this. My favorite movie is, in fact, Wind River by Taylor Sheridan, and I do not believe I’ve ever given my friend any reason to think I have any particular attachment to Despicable Me. The ice cream itself wasn’t even particularly appealing to me, and I only ate a few spoonfuls of it before leaving it in my fridge.

I’ve been conflicted as to whether or not I should follow through with my promise to pay him back for this ice cream. I don’t believe my friend would knowingly deceive me as a way to take my money, and he has been very trustworthy in the past. However, my agreement to pay him back was, in my opinion, made under false pretenses (those being that the ice cream would represent my favorite movie, and that it would be something I would deeply enjoy). Additionally, based on all the times we’ve spoken, I do not believe my friend could, in good faith, assume my favorite movie to be Despicable Me.

My friend’s girlfriend also had a great deal of influence in both my friend’s decision to offer me the ice cream in the first place and convincing me that I should pay for it. Her motives are less easy for me to ascertain, and I would not preclude the possibility she acted with malicious intent. With all that being said, I still consider agreements made between friends to be important to uphold, especially those involving money, and since I agreed clearly to what my friend was offering, I still wish to be considerate of his position, even if I feel deceived. Given this, WIBTA if I broke my promise and didn’t pay him back?