Love and heartbreak are two ingredients that often help make beautiful music. However, when our favorite artists fall in love and break up with each other, does the music soar or sour?

Some artists thrive on heartbreak — after actress Ava Gardner broke crooner Frank Sinatra's heart, he made a beeline for the studio and gave perhaps his finest performance on "I'm a Fool to Want You." P. Diddy always considered J. Lo his Ava, and ironically his career resurgence came after she left him. Conversely, Jessica Simpson and Nick Lachey's love affair launched their biggest hit. We hooked up with Cupid to figure out if romantic harmony equals musical harmony ... or not.

Jennifer Lopez and P. Diddy

Love story: Hot producer/rap mogul shares a dance with ambitious actress in the video for "Been Around the World," from his first solo album, and starts an off-camera romance. They quickly became hip-hop's highest profile couple, and Combs lent his producing talents to Lopez's debut joint, On the 6, and follow-up, J.Lo. However, in late 1999 the couple became embroiled in a shooting scandal that had Combs facing weapons possession charges. Things got a little hot for J. Lo, and a heartbroken Combs announced their breakup on Valentine's Day 2000. Lopez tied the knot with choreographer Cris Judd a mere eight months later.

Chart story: There is little doubt that having Diddy twiddling the knobs on both her albums helped Lopez's musical career — both On the 6 and J.Lo went multiplatinum. Diddy however, was in a professional and personal slump right before Lopez left him. Her departure, though, seemed to spur a new spate of creativity from the multitasking performer, including two top 10 album debuts, movie roles, the Sean John clothing line and the infamous name change.

Cupid says: While speculation abounds that Diddy's hit "I Need a Girl," which has been on the Billboard Hot 100 for 20 weeks, is about Lopez, a reconciliation seems unlikely. J.Lo is in the midst of a very public romance with actor Ben Affleck, and Diddy has been seen with his baby's mama, Kim Porter, frequently.

Gwen Stefani and Gavin Rossdale

Love story: Meeting when their bands No Doubt and Bush toured together in 1995, the two carried on a sometimes rocky long-distance relationship until Gavin proposed on New Year's Day 2002.

Chart story: While Bush's recent albums haven't scored the numbers their 1994 multiplatinum debut, Sixteen Stone, did, Gavin contributed his first solo single, "Adrenaline," to the "XXX" soundtrack. Gwen's famously personal lyrics, which seemingly chronicle the ups and downs of her relationships (see the less-than-subtle "Marry Me" from 2000's Return of Saturn), have only fueled her band's success. No Doubt's latest album, Rock Steady, has sold more than 2 million copies, and the single "Underneath It All" (a love song if we ever heard one) has spent the last six weeks on the charts.

Cupid says: Recently wed twice (September 14 in London, September 28 in Los Angeles), rock's cutest couple seems set for wedded bliss. However, they haven't hooked up in the studio over the past seven years, so we're not holding our breath for a Gwen and Gavin duet.

Madonna and Guy Ritchie

Love story: As is the case with many couples, Madonna and Guy Ritchie met through mutual friends. Granted, their friends are Sting and his wife, but it was a fitting way to start a high-profile romance that landed Detroit-born Madonna in London, with a new child and director husband.

Chart story: Family life seems to agree with the "Maternal Girl," at least musically. Her last studio album, Music, went multiplatinum, and brought with it a record-breaking tour and a title track that can still get stuck in your head for days. However, the usually collaboration-savvy Madonna has found it rough going onscreen since hooking up with Ritchie, as the duo's "Swept Away" opened to anemic numbers at the box office. While Ritchie is best known as a cult film director, even Brad Pitt couldn't turn "Snatch" into a hit. Madonna should know better after teaming with ex-husband Sean Penn on the flop "Shanghai Surprise" in 1986.

Cupid says: We're hopeful that working together on one of the biggest major studio bombs of the decade won't have an adverse effect on this love match. After all, maybe it will prompt Madonna to spend more time on her music ... Guy can always direct the videos.

Britney Spears and Justin Timberlake

Love story: After a well-documented meeting on the set of "The Mickey Mouse Club" at a young age, the pop power couple went public with their love at the 2000 MTV Video Music Awards. Earlier this year, the media engaged in an "are they or aren't they" feeding frenzy about their much-denied and finally confirmed breakup.

Chart story: While the power couple broke all kinds of sales records during their relationship, it's tough to point at any specific songs that relate to the ongoing affair. What is obvious is that their relationship helped both careers by bringing them into the spotlight, helping Justin break out as an individual from his boy band roots and helping Britney cultivate a more mature image. Justin's hotly anticipated solo album, Justified, should offer some clues to his state of mind, but Britney is keeping quiet during a well-earned hiatus.

Cupid says: These two cuties are both in their early 20s, and with the tabloids linking them to every star under 30, we see a lot of love in the future. Just not together.

Kid Rock and Pam Anderson

Love story: When Kid Rock met model/actress Pam Anderson backstage at VH1 Divas Live at New York's Radio City Music Hall, it was drama at first sight. While Pam isn't a musician, she's been in enough videos and with enough rock stars to qualify as a muse. Kid Rock proposed to Pam last April, and, after the announcement of her hepatitis C and ongoing legal struggles with ex-husband Tommy Lee, it looks like the nuptials are now imminent.

Chart story: While Rock may still be the American badass, the truth of the matter is his latest release, Cocky, just didn't have the impact of Devil Without a Cause. Never reaching higher than #7 on the charts, Cocky has come nowhere near the multiplatinum heights of Devil. It could be argued that it's tough to be a man of the people with the world's most infamous beauty on your arm.

Cupid says: We've never seen two people more perfect for each other.

Jessica Simpson and Nick Lachey

Love story: These two sweethearts have had a relatively drama-free romance since meeting when Jessica opened for 98 Degrees' tour in 1999. With the exception of a short breakup in April 2001, it's been smooth sailing, right up to Nick's proposal this February.

Chart story: Lachey's group, 98 Degrees, hit the big time in 1998 with their second release, 98 Degrees and Rising. While the single "Give Me Just One Night (Una Noche)" from 2000's Revelation was the most added single in top 40 radio history, rumors of an imminent breakup caused the group to announce a hiatus early this year. Nick recently announced a planned solo album, set for early 2003. Jessica crossed our radar in 1999 with her power ballad breakout single "I Wanna Love You Forever." Interestingly, the relationship has not only raised both artists' profiles, but they both arguably enjoyed their greatest commercial success with the duet "Where You Are" from Simpson's debut album.

Cupid says: Obviously, Nick finds Jessica irresistible. They'll keep making beautiful music together.