My fiancee's parents paid for my fiancee, me, her sister, and her sister's fiance to go on a cruise with them. My fiancee and I don't often have time to go on vacations and we were in some really beautiful places and I thought it would make a really beautiful memory for us if I proposed on the trip.

I gave her parents a heads up so they could see it if they wanted and then did it, and she said yes and it all was very exciting. Her parents got us champagne. Her sister and her fiance were pretty upset however. They pulled me aside and told me off for doing this on a family trip and making us the center of attention. They thought I should have asked her parents for permission and said that they're upset that I didn't. My fiancee is on my side and her parents honestly seemed happy about it. Am I the asshole for not asking permission to do this?