The couple, who are both currently starring in different Broadway plays, have been heating up New York with their PDA.
Just yesterday Sienna was seen leaving Jude's apartment six minutes after he left early in the morning.
An onlooker said: "She definitely didn't want to be photographed but he didn't seem to mind."
The couple even reportedly spent Thanksgiving together. A source said: "Jude has told his ex-wife Sadie that Sienna is back in his life. Sadie is calm about it, her only concern, as ever, is their children. They have never stopped caring about each other."
They've both had really bad luck in love in the past few years so maybe that's what they're bonding over!? Who knows with these two!
What do you think about them rekindling their romance? Is it a good idea or should they just stay friends?