Emma Roberts -- In Tears with Boyfriend Evan Peters

Emma Roberts got extremely emotional Tuesday, but BF Evan Peters was by her side -- on the heels of news she'd been arrested for a domestic violence incident involving him.

Emma was seen bursting into tears ... as Evan comforted her outside a New Orleans studio.

TMZ broke the story ... Emma was arrested July 7 in Montreal after she and Evan allegedly fought in their hotel room. Police say there was evidence she'd bitten him.

Evan did not want to press charges, and Emma was released.