WhatsApp Inc. Chief Executive Officer Jan Koum, whose mobile-messaging company was acquired by Facebook Inc. for $22 billion this year, is apologizing for behavior that led to a restraining order against him in 1996. The order was granted in February 1996 in state court in San Jose, California, after a civil harassment claim from an ex-girlfriend who details multiple incidents from June 1995 to January 1996 in which she said Koum verbally and physically threatened her, according to court documents. The incidents included changing her school records and preventing her from attending college classes, according to the documents.