"(Robbie is a) great guy," a source tells the website."They are in an exclusive relationship and Lizzie is excited about him. It's very new though, but they seem to like each other a lot already." The 28-year-old was previously engaged to actor Boyd Holbrook, but the couple split in 2015.Mary-Kate had the best response to the “why older men” question back in 2012.
Meanwhile, Ashley's younger sister Elizabeth Olsen has sparked rumours she is dating singer/songwriter Robbie Arnett after they were photographed walking hand-in-hand in New York earlier this week.
The Avengers: Age of Ultron star and Arnett were spotted in the city on Monday and, with reports that they have been dating since last month. Online, Olsen and the Milo Greene star met while vacationing in Mexico.
They then confirmed their relationship with a kiss while on a double date at Madison Square Garden for a New York Knicks basketball game with Ashley's twin sister Mary-Kate and her husband Olivier Sarkozy.
The former couple also attended Ashley's friend's wedding in Mangawhai, New Zealand last month.
Mary-Kate Olsen was spotted sporting a gold ring on her left ring finger Sunday, and rumors have been swirling about the accessory's implications for the designer, 26, and boyfriend Olivier Sarkozy, 43.