Now, there are reports the 20-year-old is dating 27-year-old financier Joshua Kushner.
Kushner has a connection to the Trumps: his brother, Jared, is married to Donald's oldest daughter, Ivanka.
Their waiting rooms are supposed to be great, though!
Back in October, Mack was seen escorting Emma to see the Broadway show , a hip-hop musical about the Founding Fathers.
Mack was educated at Princeton, along with his identical twin brother Robert Tyson Knight, who also goes by his middle name.
Us Weekly reports: "They are really cute together," a source tells Us of Kloss and her handsome beau, a social gaming entrepreneur and venture capitalist who's pals with Ashton Kutcher (a successful dot-com investor in his own right).
At Lavo, the insider continues, the 27-year-old Instagram investor "seemed nervous and shy around everyone but handled it well. She stuck close to him." Victoria's Secret had no comment.