Love is love. I met my partner at a restaurant not all that different from this. I didn't propose in front of the restaurant but the restaurant does have special meaning to us and we have gone back there even though we live far away from it.

I also have a friend who actually proposed with the taco bell "will you marry me" hot sauce because taco bell was their place.

Now if you just randomly proposed in front of a fast food restaurant that had no special meaning to the two of you then yeah, you fucked up