Aniston, 44, and 41-year-old Theroux, who have not finalised any plans yet, are said to be madly in love with each other, reported Contactmusic.
"The actress and her fiance who got engaged last August are still madly in love and their wedding is still definitely on even though they are too busy to plan it," a source said.
The former 'Friends' star, who is currently filming her new movie 'Squirrels to the Nuts', has been regularly visited by Theroux on the set.