The documentary begins with Rodrigo and her producer, Dan Nigro, looking back at the first song they wrote together back in early 2020. While never released, the lyrics that fans hear in the doc seem to hint at Rodrigo and Bassett's split after their rumored romance.
"Crying in the parking lot / You don't know what you want / Gave you everything / I guess everything ain't enough / You say you lost your best friend / How do you think I feel / You say it's over again / And this time it's real," she sings.
"I was so sad when we wrote that song. Oh my god," Rodrigo tells Nigro during a March 2021 studio session. "I remember that day. I was so f**king sad. It was a long time ago. And I'm still not over it!"
For Rodrigo, the relationship that plays out through Sour is "the heartbreak that kept on giving."
"I was in this situation where I had to see him, he was with someone else, which was devastating to me," she says, seemingly alluding to Sabrina Carpenter, a fellow Disney star who was linked to Bassett after his and Rodrigo's reported split. "I felt like my world was ending almost every day. Nobody understood how I was feeling or related to it, so I think by writing songs about how I felt, I was creating a friend for me."
One of those songs is "1 Step Forward, 3 Steps Back," which Rodrigo wrote the day before the guy in question broke things off.
"I remember not being able to listen to it for a while," she recalls. "I think loving someone who’s so inconsistent is so challenging, and just really anxiety-inducing. It makes you feel so insecure. It’s a really tough thing to feel like you’re walking on eggshells around someone you just want validation and love and support from. You feel like you can never really settle into that feeling of being loved and accepted."
Then came "Drivers License," the song that changed everything for Rodrigo. In the doc, the singer reads a journal entry from July 13, 2020, the day she got her driver's license.
"I realize part of the reason I wanted to get my license so bad was because of this boy. I always felt bad about being too young to drive over to see him, too young to have any real freedom. I always thought he should be with a girl who had those liberties," Rodrigo reads. "I feel this hold on me loosen more and more lately. That’s a lovely feeling. I’m still not able to fall for anyone else, though. Like, I can’t even fathom it at the moment."
Speaking about her breakout hit later, Rodrigo reflects on the line from the song that really resonates with her.
"The second verse is, 'Today I drove through the suburbs and pictured I was driving home to you.' That line can very literally be, 'I was driving home to your house,' but at that time I was really reconciling with the fact that sometimes when you love a person so much and you spend so much time with them, that’s who you feel the most at home with," she explains. "I remember listening to that song -- even when I hadn’t put it out, when I just had the demo of it on my phone -- sometimes I’d drive around and listen to it. Every time that [line] came on, my stomach would drop, just 'cause I felt like it was so acutely how I was feeling."
Given the massive success of "Drivers License," Rodrigo was nervous to release another track, largely because "there was so much drama that was around 'Drivers License,' and so much hate." She worried that putting out "Deja Vu" would mean she was "playing into this drama, love triangle, let’s-hate-on-other-girls thing."
"I didn’t want to do that," Rodrigo says. "I never write any of my songs from that point of view, because that’s not how I feel."
"Deja Vu" did become her second single, but it was with another track, "Favorite Crime," that Rodrigo was able to explore the mistakes she made in the Sour relationship.
"In order to get over a heartbreak, I think you have to forgive that person who caused you pain, but I think also a big part of it is forgiving yourself," she says. "I really like the lyric, 'One heart broke / Four hands bloody.' Having the blame be on two people. Heartbreak is a two-way street. You couldn’t have gotten your heart broken if you didn’t put yourself in the position to be hurt. I think writing this song sort of helped me forgive myself."
While Rodrigo did forgive herself, she still struggled with the split, especially when she considered if she was good enough for the boy in question.
"I was just feeling this soul-crushing inferiority. Inferiority that, I think, only occurs when you are really, deeply in love with someone," she says of writing "Enough for You." "Feeling like you’re not good enough for someone who’s your absolute world is so, so crushing."
That feeling is also brutal, an emotion she further explored on the track of the same name, which was the last song to be written for Sour.
"That period of my life is very strange," Rodrigo says of dealing with her rising fame. "I remember feeling lonely. I remember wanting a boyfriend very bad. I remember that was during a time when I looked through what people said about me online or in print. I was still reeling from this heartbreak and all of the drama that went all around it... It’s just like everything was coming to a head."
Once "Brutal" was finished, the album was too. "Hopefully I won't be as sad for the next f**king record," Rodrigo tells Nigro in the studio as they celebrate the end of Sour.
Even though she did have to go through that heartbreak, Rodrigo is grateful for every part of her journey.
"Coming from this place of hurt and devastation and you manage to turn it into something that you're proud of, and something that other people can enjoy, and something that brings acceptance and light and joy into the world, there’s nothing better than that," she says. "There’s not a day that goes by that I’m not grateful for the opportunity and so proud that I did that too."
"I’ve grown, like, five years' worth in a year. I think I’m so much of a different person in a good way. I think I had to learn how to have thick skin and how to stand up for myself," Rodrigo continues. "I think I just wanted to tell people what was going on in the depths of my heart and the back of my head in a way that was proud. I think there’s something so powerful about that, especially as a young woman."
As the credits on the documentary roll, fans get one last peek into Rodrigo's heartbreak, as a previously unreleased track plays.
"I know you’re with somebody new / I can't write a song that’s not all about you / It’s no fair baby / How come it’s so easy for you to forget everything you said / Like how I was the best girl that you’ve ever met / Guess you take it back / Should have expected that," she sings. "When I say I’m fine / I’m lying really well / 'Cause I can’t love anyone else / And I’m so jealous that you can / Scared I’ll never feel that again / 'Cause I still can’t call anyone baby / 'Cause baby is still you to me / Don’t you think I want to move on too / But I can’t love anyone the way I loved you."