To me personally, celebrity relationships are important news only as much as anyone's relationship that I know and care about are. Unfortunately it is our nature to want to know every last detail about people in the spotlight so I have to agree and say that to the majority of us celebrity relationships are compelling if not important news.
People want excitement in their lives. Most of us don't get much excitement in our daily existence, so we look for it from our celebrities. With the easy access provided by news outlets and the internet, we can easily see who's romancing whom. When a celebrity relationship fails, we don't feel so bad that our own relationships aren't perfect.
Celebrity marriages are not important news stories. Our society places way too much interest into the lives of the rich and famous (rich and infamous). It does not matter which celebrity is dating/marrying which celebrity. People should be more concerned with their own lives; instead of being fascinated by celebrity news.
Maybe it is important to know when a celebrity dies. But their relationships are as private or as public as they want them to be. Most importantly a celebrity relationship does not need to be headline news, particularly in every newspaper. We have become way to involved in the private lives of entertainers.