The £145million signing has tattoos on his arm dedicated to childhood sweetheart and every goal celebration goes out to her
Through nearly every step of his career, from Vasco da Gama to Liverpool via Inter, they have been together.
And not even a brief spell living apart when the £145million man was on loan at Espanyol could throw their relationship off track.
No wonder Coutinho seems destined to fit in so well in Catalonia.
Lionel Messi married childhood sweetheart Antonella Roccuzzo in a lavish ceremony in their native Argentina last summer.
And team-mate Luis Suarez had to endure a long-distance relationship with then-girlfriend Sofi when he started his career at Nacional.
They have been together 15 years and Sofi has even been credited with inspiring the Uruguay star to become the player he is today.
This familiar Barcelona tale of romance and young love is found again in Philippe, 25, and 24-year-old Aine.
The pair met in 2007 when the promising footballer was just 14 and they grew up together in Brazil's capital Rio de Janeiro.
A mutual friend introduced them to each other at a party and they began dating, living together under the same roof as Philippe's mum Esmerelda and dad Jose.
Aine would travel with him watching every game.
Philippe signed for Internazionale in 2008 before returning to Vaso de Gama for two season.
However, it is believed that when Philippe went back to Italy in 2010 Aine stopped her studies and went with him.
It is believed they were forced to live apart for a short while when he went on loan to Espanyol in 2012 but later married that same year.
When Philippe signed for Liverpool in 2013 they moved there together.
Although the forward's struggle to break into the first team meant Aine had to sit in the stands with everyone else to watch her man play, judging by the photos of tickets she put on her social media accounts!
Since then they have welcomed two children into the world, daughter Maria and son Philippe Junior.
And the Brazilian star has shown his dedication to his loved ones by tattooing reminders of them - Aine, his mum, dad and two brothers - on his left arm.
Philippe has said of his wife: "Aine plays a huge part in everything I do. We didn't study together, we didn't really have mutual friends, except for one, who had a party and we both went to it. We met there and sat together for a long time just talking.
"She asked me to be her boyfriend.There wasn't really a moment where we were like, 'OK we are together now.'
"We're from the same neighbourhood and so we just started seeing more and more of each other, going places together and it grew deeper and stronger."
He now dedicates every goal celebration to her, blowing kisses in her direction.
Expect to see a lot more of that, and Aine smiling in the stands, at the Nou Camp.