The relationship between Phoebe Halliwell and Coop Halliwell began in the latter part of Spring 2006. Though their time on-screen was short, they fell in love and became a couple very quickly.
Phoebe and Coop's relationship is continued on in the Charmed comics where they were shown to have married and had one child since 18 months after the Ultimate Battle with Christy, Billie and the Triad.
In a flashforward of Forever Charmed, they are seen getting married and having three daughters together.
Season 3
The initial of Phoebe's true love.
In season 3 episode All Halliwell's Eve, Phoebe and her sisters travel back in time to when Melinda Warren is born. Here, Phoebe learns that the first letter of her true love's name is C. This prophecy is doubly fulfilled, both when Phoebe finds her first great love, Cole Turner, and when she marries Coop.
Season 8
Their first kiss
Coop and Phoebe first met when she accidentally bumped into him. Phoebe, however, did not even give him a second glance, which Billie brought to her attention. Later that day, Coop again came across Phoebe and told her he was her new neighbor. Phoebe being suspicious looked into his so-called apartment and found nothing. Later, when she confronted him he revealed himself to be a Cupid sent by the Elders to help her find love.
Phoebe disliked Coop at first and was annoyed that the Elders would think she needed help finding love, but Coop knew that she was just scared because of all her previous heartbreaks and disappointments; he reassured her that her future daughter was destined, but she had to find love first. Phoebe's continued reluctance and Coop's persistence lead to them challenging, amusing and exciting each other. Phoebe eventually became comfortable asking Coop for advise and support.
A promo pic of the couple.
Coop helped unblock Phoebe's heart after spending the day time traveling looking over Phoebe's ex-loves. Coop then proceeded to find her perfect match. However, in the midst of it all, they both secretly fell in love with each other. They eventually admitted their feelings although the timing was a bit off as Billie and Christy had turned all magical creatures against The Charmed Ones. Coop, however, did not fall for the trick and professed his love for Phoebe to Victor in his search for her. When he eventually found her, she told him off due to being frustrated over the upcoming fight against Billie. Coop left but was called upon by Piper after Phoebe and Paige had died. Realizing Phoebe was dead, he willingly gave Piper his ring so she could time travel back and save his love.
Later, when Coop met future Wyatt and Chris, Wyatt accidentally revealed that he and Phoebe were married in the future. Phoebe tells Coop that she doesn't want to go through what Piper and Leo went through with the forbidden love and says they can't be together. When Christy needed to go back in time, Dumain kidnapped Coop and stole his ring. Needing Coop, Phoebe calls for him but he doesn't show. Wyatt and Chris tell Phoebe that the Elders knowingly sent Coop down to Phoebe so that they would both fall in love.
The couple kissing again.
The Elders felt that they should break the rules for Phoebe as she had given up so much over the previous eight years. Not understanding how that will help in this situation Phoebe is confused. But Wyatt and Chris tell Phoebe that in the future all she has to do is think about him and he's there. Phoebe concentrates and Coop materializes proving that she loves him. When the battle is over, Phoebe and Coop hug signifying they finally embrace their feelings for one another.
Season 8 - Charmed Comics/Season 9
The wedding
In between season 8 and 9, Phoebe and Coop started to date. After a few months together, Coop brought Phoebe to Cupid's Temple in Italy. Cupid's Temple is an ethereal location on a Cupids plane of existence. It is the home for Cupids and Messenger Cherubs. Here, Coop proposed to Phoebe who accepted. Phoebe and Coop then got married by the Angel of Destiny in the reclaimed Magic School with all Halliwells attending. On their honeymoon, Phoebe became pregnant with her first child. Nine months later, Phoebe gave birth to her first daughter Prudence Johnna Halliwell. Together Phoebe and Coop bought a new house and moved out of her condo.
Season 9
Coop and Phoebe with their first child, Prue.
Phoebe was late for work and was frantically looking for her keys. Coop watches and jokes about taking a picture of the situation. Coop reassures her that the paper can't fire her as she is too valuable. As Phoebe leaves she is beamed back. Thinking it is Coop she kisses him and apologizes for forgetting the good-bye kiss. However Coop tells her it wasn't him. Phoebe and Coop realize it was their daughter Prue coming into her Cupid Powers.
When Phoebe is forced to marry complete strangers Coop drops by to make sure she is okay. She asks him to wait as she deals with a persistent couple who, thanks to her recently reclaimed empathy power, knows are deeply in love. Coop tells her that they are Romeo and Juliet. Phoebe wonders how he knows, but Coop says its every Cupids job to know about the most famous couple in history. When Juliet tells Phoebe that everyone's love is special Phoebe realizes she should be more considerate, especially since it took her so long to find her love Coop.
After all innocents had been found Phoebe asked Coop to recheck the book for anything she missed but he finds nothing. Heading downstairs Phoebe and Coop discuss the savageness of the house guests especially the person (who Coop hoped was a guy) that peed in the kitchen sink. Suddenly Coop and Phoebe are attacked by the spellbound innocents. Phoebe reminds Coop that because they are under a spell they can't hurt them. Wondering what they should do Phoebe tells him to run. They retreat to the attic where they meet Paige who says they should head to magic school. Phoebe, Coop and Paige all go to magic school. Later when Phoebe returns from her first fight with the resurrected Source he helps her to her feet.
Piper asks to borrow Coop to go to the attic. While there Coop tells Piper that Phoebe had told him all about what the Source and Shax did and that he understands her anger. Later when they are all preparing for the fight Coop asks to stay and help but Phoebe does not let him. She says that someone needs to be there for Prue if she doesn't make it. Coop tells her that he knows that they will stop the Source and reassures her just before the Source attacks. Later once the Source was stopped Phoebe and Coop went to the location of Piper's new restaurant.
Coop comforting Phoebe.
When Phoebe finds out that her friend Mika is dating Cal Greene, the man she saw herself killing in 2009, when she went to the future in 1999, she becomes worried. Sensing that Phoebe is worried, Coop once again takes her to Cupid's Temple so that Coop can help Phoebe with her problem. Coop calls in a favor and asks a Messenger Cherub if Mika and Cal's love is real. Coop finds out that they are in love but it is not destined to last. Phoebe is worried that this means Cal kills Mika but Coop staying positive informs Phoebe that this means that she can break them up without interfering with true love. Around one week later Phoebe finishes her story about trust and spends some time with her family.
Near the end of the season, Phoebe and Coop have another daughter, whom they name Parker.
Season 10
Phoebe and Coop's third daughter, Peyton.
Phoebe and Coop continue to live together. Coop is very understanding and supportive toward Phoebe when Cole died. However, Coop's involvement in the Charmed Ones' demon hunting activities is interfering with his work as a Cupid, which upsets his superiors. Coop comforts Phoebe after Cole sacrificed himself to save him.
When Benjamin Turner possessed Coop, he was able to see Coop's memories, and through them, his son's history with Phoebe. The pair is eventually separated by the Court of Love, who deemed Coop's recent activities unfitting for a Cupid, and only allowed them to reunite one day every year on their wedding anniversary. Phoebe realizes she is pregnant with her third daughter right afterwards.
During his absence, Coop and Phoebe try to repeal the decree, only to realize he was being kept by the Tribunal for protection from an grave threat. Phoebe later has a premonition of Cole being choked by a possessed Prue, and rushes to Cupid's Temple to save him. However, Prue is too powerful for her, and Piper and Paige (who arrived moments later) to handle, and only managed to escape, without Coop.
They eventually free Coop during a fight in Salem, and Phoebe and Coop escape back to Magic School. However, after the Power of Three shifted back to Prue, Phoebe cast a spell remotely to make Prue come to her senses. Seven months later, they have their third daughter, named Peyton.
The Future
Phoebe's book: Finding Love.
In the future, they are seen living happily raising their children. Phoebe and Coop's three daughters will eventually have children of their own, providing Phoebe and Coop with grandchildren. Phoebe continues to work as advice columnist, both giving advice to those who asked and publishing a book to help people find love, called "Finding Love".