The couple began dating after meeting on the set of ill-fated "Fantastic Four" reboot in 2014, a film in which they starred as Sue Storm and The Thing, respectively. Mara and Bell marked their public debut as a couple at the 2015 Met Gala.
The marriage will be Bell's second. He was previously married to Evan Rachel Wood from 2012 to 2014 and they share a son. As for Mara, this will be the 33-year-old actress's first marriage. Her first highly-publicized relationship with fellow actor Max Minghella lasted nearly four years.