The longtime duo, who met on the set of their film Fantastic Four in 2014, have been dating since 2015 after first being linked during a Met Gala after-party where they were seen holding hands.
The 33-year-old actress was spotted wearing a dazzling diamond sparkler on her ring finger in New York City several times this month, which sparked rumors that the pair were set to tie the knot. Mara also showed off the same gorgeous rock in a photo she posted to her Twitter account last week that featured her decked out in football gear.
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This will be the first marriage for Mara, and the second for Bell. The 30-year-old actor was previously married to Evan Rachel Wood—they called it quits in 2014 after two years of marriage and share a 3-year-old son.
We wish the duo all the best.