Roberts, 24, and Peters broke off their engagement earlier this year, but are frequently spotted together now, reported Entertainment Weekly.
The couple was recently seen holding hands after a shopping trip to the mall.
The two are "seeing each other again," a source said.
Last week Peters, 28, and "We're the Millers" actress were all smiles as they left an eatery in Los Angeles before heading home.
The couple got engaged back in 2013.