Serena Williams has recently for engaged to Alexis Ohanian. The engagement of a famous athlete to a business co-founder is far more newsworthy than the engagement of two average citizens. More people have heard of Serena Williams than your average Joe, I would personally not be interested in hearing about Bob from Wisconsin getting engaged.
Yes, the engagement of a star athlete such as Serena Williams is more newsworthy than the engagement of the average citizen. Even though other people's engagement is important to them, far more people find it interesting to know that Serena Williams is getting married than the average citizen. Furthermore, people want to know who she is going to marry.
It matters to society when wealthy or business people decide to join assets. They might make decisions together that affect other people. Also, if someone is a fan of Serena Williams they might be interested to know what is going on in her life. They might be happy for her, or they might wonder if she's going to stop paying tennis.
While I'm very happy for them and wish them all the best in the future, I really couldn't give a hoot about Serena and Alexis' engagement. It has no impact on their ability to preform either of the things they are famous for, so I'm not really sure why it should be our business.