River was the name of Joaquin’s late brother, who died at the age of 23 in October 1993.
Phoenix has reportedly been engaged to fellow actor Rooney Mara since last year.Although the couple have not confirmed the engagement themselves.
In 2019 Phoenix told Vanity Fair magazine: “She’s the only girl I ever looked up on the internet...we’re just friends, email friends. I’d never done that. Never looked up a girl online.”
They confirmed they were still a couple at the Cannes Film Festival in 2017 when they sat together and held hands.
And at the Toronto International Film Festival in 2019, when accepting his Tribute Actor Award, Phoenix gave Mara a slightly strange shout-out, saying: “One last thing - somewhere here, I don't know where, is a filthy dragon, and I want to rip its wings off and fasten a blanket and sleep with it forever. I love you. Thank you.”
Reports they were expecting a baby circulated earlier in 2020, but neither commented on the news, keeping a low profile at home in Los Angeles.
The pair are both vegan and dedicated animal rights activists. They have previously been pictured taking part in animal rights protests.
Phoenix previously joked about being engaged to his yoga instructor. In 2014 he told ‘Good Morning America,’ “I think my life is so boring and it seemed like something exciting to talk about and I wanted the audience to like me.
“They really like people getting married. I can get engaged again, if you like.”
In a statement his spokesperson reportedly said that “Joaquin has an extraordinary and spontaneous sense of humor but it is not true.”