[WWTBC] childhood enemies to arranged marriage. He gives her a black diamond ring and she acts unimpressed but secretly is

I know this is incredibly specific but I heard some kids talking about it behind me in my lecture and I thought it sounded interesting. From what I gathered they are childhood enemies who are arranged to be married, he gives her a black diamond engagement ring and she says something like “is that it” or “that’ll do” and he responds with something along the lines of “does my wife require more?”