Musa and Riven met in Season 1. Musa developed a crush on him, but did not get to know Riven that well because of the spell Darcy put on him at the beginning. They were friends in Season 2 and became a couple at the end when Musa kissed him. Starting in Season 3, they argue a lot as a couple. Even though it appears that they do not seem to love each other much because of their arguments, it is revealed other wise in Season 4 when the boys are kidnapped, each time Musa gets on stage by Riven's jealousy and anger and by each of Riven's attempts at showing his love to her. Riven even writes a song for her in Season 5.
When she first sees him in Black Mud Swamp, Musa immediately falls for him and she confesses to her mother on the Day of the Rose. That same day, Riven is injured in a Wind Riders race by the helmet Bloom gave him to make peace. Darcy heals him and he goes with her, thinking his so called "friends" do not want him any good. When Musa sees Darcy and Riven together in a witch bar, Icy, Stormy and the witches run after her in Magix after she slapped Icy. When she ran by Riven, she asks him to help her, but he is almost laughing at her asking her why he would help her. She is heart broken and, in tears, runs away.
At the start, when Stella, Bloom, Aisha, Sky and Brandon are leaving to save the Pixies, Musa glares at Riven in Alfea quad, but some days later, she is so worried for them she throws herself in his arms crying. He wraps his arms around her but, when she tells him to not tell anyone she cried, lets them fall.
In the Wildlands, Musa and Riven argue but finally reconcile when she finds him spying on the Trix. Riven wants Musa to watch them while he goes and warn the others of their presence, but Musa decides otherwise. She chooses to trust him by letting him spy on them and tells him she likes him, earning her her Charmix.
At the end, before entering Darkar's Fortress, Musa mocks Riven, telling him that he is not all into the mushy stuff, but Riven pulls Musa in a hug, admitting to her he does not know what he would do without her and asks her to promise him that she will come back to him.
During the fight to save Bloom, when Musa is about to be struck by Darkar, Riven runs in front of her, getting injured. Musa goes to Riven's side trying to wake him up, when she gives up, she kisses him. However, as Bloom used her healing power to heal everyone, Musa is flustered when Riven opens his eyes and scoots away from him, as she did not want him to know she loves him.
Their relationship starts going down hill when Riven states to Bloom that seeing Sky and saving him from Diaspro's spell was useless. Upset at his attitude, Musa scolds Riven. They don't talk very much, notably during the crying session among the Winx and Timmy after Tecna fell into the portal to the Omega Dimension, but Riven looks at his girlfriend when he tells Timmy he knows what he means when he said he still felt Tecna's vibrations.
Musa considers breaking up with Riven after they train to become stunt bikers to save Stella's father. When the Winx and Specialists, except Riven and Helia, go to the Red Tower for the Water Stars, Riven thinks Musa is cheating on him when he sees her putting handcuffs on Nabu in the video Flora sent to Helia. Without hesitation Riven takes his wind rider to go the Red Tower. When he arrives with Piff, he sees Nabu with an injured Musa in his arms. Not believing it is only because she needs help and because he loves her and is afraid to lose her, Riven orders him twice to put his girlfriend down and after jumps on him to fight. When they are separated, Musa and him talk and reconciliate.
Later, when the Specialists where kidnapped by Valtor and the Winx, Nabu and Helia go to rescue them, Musa is almost crying when she sees a stoned Riven, who she believes is the real one. At the end, when everyone believe Valtor is defeated, Musa and Riven kiss.
Mandragora hypnotizes Riven, and turns him into an antagonist. When the Winx are about to open Obsidian, Riven takes the key from Bloom. Sky fights with him for that key and, as Riven is about to stab Sky, Musa jumps betweent the two, getting injured. She becomes unconscious and Riven is upset, remembering memories of the both of them, shedding black tears. The spell is broken and his love for her heals Musa. Hugging, Riven confesses to Musa that he now knows who he is fighting for, for her. She is pleased with that and they kiss.
At the start of the season, Musa and Riven are seen happy together. The Specialists are secretly sent to Gardenia to watch after the Winx. Riven's jealous side is shown by his anger when he sees Musa singing on stage with Andy. When the Winx discover their presence, Musa and Riven start arguing once again. They reconcile after the magic pets attack, when the Winx admit they needed the Specialists' help and they that their girlfriends can fight alone.
Days later, Musa shows off her musical talent on stage with Andy, angering and jealousing Riven for all the attention she was receiving. Jason Queen, a music producer, discovers Musa and her singing ability and offers to make her successful. Taking the deal, Musa is excited but is shortened out by Riven. Showing no support and insulted that he thinks she could have sing better at the audition, Musa ends her relationship with Riven, stating that she would rather be with those who do support her.
While fighting against the Wizards of the Black Circle, Riven asks Musa how she was able to tell the difference between him and the copy of him, to which she replies that he likes to fight alone. Their relationship continues to be tense for a long time.
Trying to win Musa back Riven attempts to show her that he truly loves her and supports her, he takes Helia's advice and decides to try and help her out with with her music career. Riven tried to help by coming up with lyrics for her new song and tried giving her flowers and chocolate's to show his love and support for her. However, this only makes Musa angrier as she thinks he only wants to ruin her music projects. But when Nabu explains to her what Riven was trying to do, she calms down and apologizes to him, but she says to him that even though she appreciate's what he was trying to do she says she needs to be alone for a while.
However, when Diana kidnaps the Specialists and Nabu tell the Winx, Musa cries and says that she loves Riven so much and she is so scared to not see him ever again, that she does not want to lose him and that she regrets they have been arguing a lot. When they reunite, Musa and Riven hug, happy to be together and that each is not injured. Riven and Musa say they missed each other.
They finally talk everthing through on the beach and, joking, when Musa says they cannot be together anymore and Riven asks only for the reason, Musa starts laughing and says: "because I'm already yours".
Days after, at the park, when the boys announce they have to go back at Red Fountain, Musa starts crying because she will not see him and they got back only a few days ago. Riven reassures her saying he will be back soon and they kiss.Musa and Riven, except that they kissed when the Winx arrived in Eraklyon.
Musa and Riven are getting close. They're getting closer and closer until Musa becomes jealous that Riven is hanging out with a blond fairy. In "The Shark's Eye", it is revealed that the blonde fairy only gave Riven guitar lessons. Then he is proving to Musa how important she is to him by singing a song to her. She eventually joins in and they sing together.
In episode five, Musa excitedly tells Riven that she is visiting the Golden Auditorium. Her call interrupts him training and they talk briefly, leaving her upset, wondering why she continues to try. In that season, Riven starts to care more about being the best fighter in Red Fountain by training almost every day, which leads him to always be busy and seem to care less about Musa. In episode twenty-three when Musa gets her voice back, she and Riven agree that they are not meant to be and break up.
As a couple, Musa and Riven have songs sang either by one of them or both: