Beyonce and Jay Z perform at the 56th annual Grammy Awards on Jan. 26, 2014, in Los Angeles. (Photo by Kevin Mazur/WireImage) | Kevin Mazur via Getty Images
When they're feeling extra lovey-dovey, celebrity couples hit the recording studio together. It's like a rite of passage for Hollywood's hottest musical pairs. But exactly how romantic are these infatuation-driven duets? From Jay Z and Beyonce to Sonny and Cher, we put 15 songs to the test, assigning each a "heart beats" rating that ranks romance factor on a scale of 1 to 10. Usher in Valentine's Day with these love songs, and chime in with your favorite celebrity-couple duets below.
Jay Z & Beyonce -- "'03 Bonnie & Clyde"
Released: 2002, even though we technically didn't know they were a couple at the time.
Heart beats: 6. This one's more about luxury gifts than true love, but Bey and Jay abound with partner-in-crime infatuation.
Most romantic lyric: "Only time we don't speak is during 'Sex and the City' / She gets Carrie fever, but soon as the show is over / She's right back to being my soldier"
Heart beats: 3. It's about a rough breakup, but the end reveals they've both found someone else. Yay?
Most romantic lyric: There aren't any. "You came back to find I was gone / And that place is empty / Like the hole that was left in me / Like we were nothing at all." Heavy stuff.
Still together? Yes, they got married in July 2013.
Sonny & Cher -- "I Got You Babe"
Heart beats: 10. You probably started singing this classic the second you read the headline.
Most romantic lyric: "So let them say your hair's too long / 'Cause I don't care, with you I can't go wrong / Then put your little hand in mine / There ain't no hill or mountain we can't climb"
Still together? Cher and Sonny Bono's relationship began to unravel in the late '60s in the wake of their sudden career woes. They maintained public appearances until finalizing a divorce in 1975. Bono died in 1998.
John Mayer & Katy Perry -- "Who You Love"
Heart beats: 7. This could be a hippy-dippy free-love anthem if it weren't styled like an adult-contemporary canticle that doubles as hold music for a 1-800 call.
Most romantic lyric: Oh, you can't make yourself stop dreaming / Who you're dreaming of / If it's who you love / Then it's who you love"
Still together? It depends on the day, but for now, yes.
Bobby Brown & Whitney Houston -- "Something In Common"
Heart beats: 6. It's a combination of sex rumblings ("I'm sweatin' for your body") and he-said-she-said romantic passion ("I'm the type of girl who understands my man").
Most romantic lyric: "Girl, you know it's you that I adore / And there's no one in this world / That I love more"
Still together? No. The tumultuous marriage ended in 2006 when Houston filed for a separation. Their divorce was finalized the following year. Houston died in 2012.
Jennifer Lopez & Marc Anthony -- "No Me Ames"
Heart beats: 4. This is one complicated relationship. Sometimes they love each other, sometimes they don't. Sometimes they're "dying in a war of regret and sad thoughts," sometimes "this great love deserves to soar through the blue sky."
Most romantic lyric: "I will always love you." Really, there aren't many choices here. And the song is in Spanish, which isn't helping.
Still together? Lopez and Anthony married in 2004 and had twins in 2008. Citing irreconcilable differences, the couple separated in 2011 and divorced the following year.
Jessica Simpson & Nick Lachey -- "Where You Are"
Heart beats: 3. It's sentimental, but it's also entirely about death.
Most romantic lyric: "Where you and I can breathe together once again / We'll be dancing in the moonlight just like we used to do / And you'll be smiling back at me / Then I will be free"
Still together? The couple apparently had problems beyond Simpson's tuna confusion. They divorced in 2006 after four years of marriage.
Faith Hill & Tim McGraw - "Let's Make Love"
Heart beats: 8. It's hard to discern whether this is soulmate love or sex-until-the-sun-comes-up love, but their vocals are passionate enough not to make you question it too much.
Most romantic lyric: "I'm so in love with you / Look in my eyes / Let's get lost tonight / In each other"
Still together? Thankfully. Country fans flipped when divorce rumors circulated last year after 17 years of marriage, but the couple called the suggestion "perplexing."
Heart beats: 0. You'd never know the duo is dating based on this thumping party anthem. "Big money is us" is not a sentiment that connotes courtship.
Most romantic lyric: "I don’t really care / Who’s in here / I’mma run this place / And this is my year"
Still together? They make for a beautiful married couple, even if Keys thought he was "so annoying" when they first met.
John Mayer & Taylor Swift -- "Half of My Heart"
Heart beats: 5. He kind of loves her a lot, he's kind of "never truly loved anything." Bummer.
Most romantic lyric: "I was made to believe I'd never love somebody else / I made a plan, stay the man who can only love himself / Lonely was the song I sang, till the day you came / Showing me another way and all that my love can bring"
Still together? LOL. As if. Do you know Taylor Swift?
Rihanna & Chris Brown -- "Nobody's Business"
Heart beats: 9. It may be painful to admit, but this one's pretty romantic.
Most romantic lyric: "You'll always be the one that I wanna come home to / Girl, let me love you and show you how special you are / I wanna be your baby, you'll always be my baby / Tell me what you want"
Still together? You know the story. They've been on and off again since 2009. For now, they're off.
Released: 1973, when a pre-Fleetwood Mac Stevie Nicks and Lindsey Buckingham combined to form a duo known, fittingly, as Buckingham Nicks. (Their efforts were not commercially successful.)
Heart beats: 4. It's kind of sweet, but we don't think "frozen love" sounds like a particularly uplifting notion.
Most romantic lyric: "And if you go forward, I'll meet you there / And if you climb up through the cold freezing air / Look down below you; search out above / And cry out to life for a frozen love"
Still together? Fleetwood Mac's bed-hopping nature has been well documented, and Nicks broke it off with Buckingham in 1976. Despite their volatile relationship, Buckingham told Rolling Stone last year that "there's a subtext of love between us."
James Taylor & Carly Simon -- "Devoted To You"
Released: 1974 (It's a cover of a Felice and Boudleaux Bryant song that was first made famous by The Everly Brothers.)
Heart beats: 10. It's all in the title.
Most romantic lyric: "I'll never hurt you / I'll never lie / I'll never be untrue / I'll never give you reason to cry / I'd be unhappy if you were blue"
Still together? Simon and Taylor's marriage lasted 11 years and gave way to two children. They divorced in 1983.
Blake Shelton & Miranda Lambert -- "Over You"
Released: 2012. The song is recorded by Lambert, but she and Shelton wrote it together. They joined forces for a duet on a May 2013 episode of "The Voice."
Heart beats: 2. It feels like a lost-love ballad, but the couple have revealed it's about Shelton losing his brother as a teenager.
Most romantic lyric: "I miss you / They say I’ll be OK / But I’m not going to ever get over you"
Still together? They've been married since 2011.
Ciara & Future -- "Anytime"
Heart beats: 10. It's not every day someone promises to go to war for you.
Most romantic lyric: "I cry happy, happy tears every night / I'mma spend the rest of my life / Just loving on you, kissing on you, being on you / Holding on you, touching on you, leaning on you"
Still together? Yes, they're engaged and expecting their first child together.
Celebrity Couples' First Valentine
They may be newlyweds, but these two only started dating last summer.
The two A-listers confirmed their relationship in January.
The comedians have been together since May.
They tried denying it, but we know it's true. The two actors have been dating since last summer.
The awfully photogenic couple may be engaged, but they've been together since last summer. True, they did have a fling in 2012, but it was a spring affair and thus did not include Valentine's Day!
The '90s stars hit it off last March.
Leo and the (currently) last in a line of impossibly gorgeous ladies have been together since May.
These two may already be married, but they've been together for less than a year. After a longtime friendship, they started dating in May.
This one is debatable. Though rumors have circled the stunning duo since filming "Rum Diaries" in 2011. Depp was still with his ex-partner Vanessa Paradis at the time. This might be this newly-engaged couple's first public Valentine's Day.
These two got engaged in January after six months of dating.
The handsome duo got together last October, after Murray called off his seven year engagement to someone else.
The beaming couple started dating in April 2013.
The camera-shy couple has been together since last July.
We're hoping he's no rebound: Watson broke up with her boyfriend of two years over the summer and by winter was seen with hunky Oxford student and athlete Janney.
This post has been updated with additional information about the inspiration for "Over You."