This week’s ouster of Nestlé Chief Executive Laurent Freixe served as a lesson to other European executives: When it comes to office romances, expect to play by American rules.

A more laissez-faire approach has traditionally prevailed in much of Europe. For years, companies and their boards largely viewed the private lives of employees—and even bosses—as mostly off limits. European authorities, too, have traditionally imposed tighter limits on employers’ abilities to monitor and investigate staffers’ relationships than in the U.S.