It's disingenuous to refer to their relationships as merely dating, when they have lasted for more than a decade. And when it's not dating, you don't really have a point.
What's disingenuous is the editor's hijacking our cultural assumption that the headline means couples who were happily married for decades have begun living separated in burgeoning numbers. If these are romances that only began in a later life stage, that should be transparent in the headline, not buried in attempted cleverness to get a page click.