Jennifer Aniston thinks Justin Theroux came up with "the most romantic proposal."

The 43-year-old actress and the actor have been dating for around 15 months and became engaged on Justin's 41st birthday August 10.

Apparently the pair were hitting a rough patch before Justin asked Jennifer to marry him. Jennifer was upset to learn that Justin was still corresponding with his ex-girlfriend Heidi Bivens, whom he was with for 14 years, without her knowledge.

Justin flew to the set of Jennifer's upcoming comedy We're the Millers in North Carolina to rectify their situation.

"[After two days of winning Jen back and] a ton of groveling, he [got down on one knee and] said, Make me the happiest man on Earth and be my wife,' " one of Jennifer's friends told Star magazine.

"The proposal totally melted Jen's heart. She couldn't resist she screamed out, Yes!' "

Jennifer is said to have made a very clear agreement with Justin about the conditions of their union.

"Jen demanded Justin immediately cut off all contact with Heidi and any other previous girlfriends he's remained in touch with," the source explained.

"And he promised to stop meeting up with other girls behind Jen's back."