Ashley and Richard were first spotted together at a Flywheel Flatiron exercise class in New York. 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.
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. According to the E! Online, Olsen and the Milo Greene star met while vacationing in Mexico.
"(Robbie is a) great guy," a source tells the website. "They are in an exclusive relationship and Lizzie is excited about him. She deserves it. 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. She was also linked to her I Saw the Light co-star Tom Hiddleston.