Naomi Watts and Liev Schreiber might be the friendliest exes of all time. The estranged couple, who separated after 11 years together in September 2016, recently reunited for a great reason: to celebrate the 10th birthday of their son, Alexander. Liev documented the special occasion on Instagram writing, "Happy Birthday Big Boy! Finally hit the double digits!" alongside a photo of them cutting his birthday cake. Awww! We certainly love seeing their sweet family moments together.