You and Denkidecided that they should do Thanksgiving at your families house since he had never met them before

plus your family had always made fun of them for not having a significant other with you, and now that they were engaged

They knew their sister would be jealous of that one. When they showed up, the first comment was

Sister: "Sissy still doesn't have a boyfriend!"

their spoiled sister giggled. Nobody knew you were engaged, Denki was running a little behind, but it was ok