Relationships are difficult enough even when you don't have to write eight to 12 songs together every two years.

But since the early '00s, there has been a tangible influx of male-female musical duos (like Sleigh Bells above) in alternative and indie rock. Maybe it's easier to collaborate with just one other person. Or maybe it's just easier to split the royalty checks from the companies you iinevitably allow to use your hit song in TV spots (check out how many of the bands below became famous thanks in part to Apple or Sony).

Whatever the reason, however, there are so many boy-girl bands in the world now that we had a difficult time narrowing this list down to 13 -- and we didn't even include You+Me (the new duo featuring Pink and Alexisonfire's Dallas Green) or the Bulls (the new duo featuring Airborne Toxic Event multi-instrumentalist Anna Bulbrook and the Duke Spirit guitarist Marc Sallis).

While a couple of the pairs that made the cut aren't around anymore, we thought they were too significant not to include. Others, though, you'll probably recognize from, you know, some commercial or another. Here are the 13 Best Co-Ed Duos In Rock:

  • 13

    Chairlift

    Originally created in 2005 by breathy vocalist Caroline Polachek with the intention of writing music for haunted houses, Brooklyn-based Chairlift (also featuring multi-instrumentalist Patrick Wimberly) shot to fame the 21st century way: their song, 'Bruises,' was featured in a 2008 iPod Nano commercial. Although the duo was actually a trio for a few years, it's been just Polacheck and Wimberly since 2010.

  • 12

    The Raveonettes

    Often drawing comparisons to the Velvet Underground for the obvious inspiration they've drawn from '50s and '60s rock and their dark lyrics, Danish duo the Raveonettes have been huge in Scandanavia since 2003 and buzzworthy stateside most of that time. Comprised of frontwoman Sune Rose Wagner and bassist/guitarist Sharin Foo, the Raveonettes released their seventh album, 'Pe'ahi,' in July 2014.

  • 11

    Cults

    Indie-pop outfit Cults formed in 2010 while guitarist Brian Oblivion and singer Madeline Follin were students in New York City, rising to prominence on the strength of a Bandcamp page. They've since signed to Lily Allen's label, In The Name Of, and released two critically acclaimed albums -- the most recent, 'Static,' provides an unofficial glimpse into the romantic break-up of Follin and Oblivion.

  • 10

    The Dresden Dolls

    One part musicians and another part avant garde theater performers, Amanda Palmer and Brian Viglione of Boston's the Dresden Dolls have described their sound as "Brechtian punk cabaret." The pair achieved widespread success after supporting Nine Inch Nails on tour in 2005 but released only one more full-length after that. Although they went on hiatus in 2008, the duo reassembled for reunions in 2010 and 2012.

  • 9

    Purity Ring

    Once members of experimental Canadian pop group, Born Gold (then known as Gobble Gobble), instrumentalist Corin Roddick and vocalist Megan James decided to splinter off into the electronics-heavy Purity Ring after Roddick asked James to sing on one of his new production projects. They signed to 4AD and released their 2012 debut, 'Shrines,' which went onto grace a ton of year-end best of lists.

  • 8

    Best Coast

    Former child actress Bethany Cosentino (you might remember her from commercials for Pepsi and Little Caesars) formed Best Coast with guitarist and multi-instrumentalist Bobb Bruno in Los Angeles in 2009 and were quickly wrapped up in internet buzz over their blend of Liz Phair-type indie and '60s surf pop. Cosentino most recently shows up in a duet with Rivers Cuomo on Weezer's new album, 'Everything Will Be Alright in the End.'

  • 7

    Sleigh Bells

    During the ages of 17-22, guitarist Derek Miller played in Florida hardcore outfit Poison the Well. During the ages of 12-16, Alexis Krauss was in a girl group called RubyBlue. But after the pair met in Brooklyn in 2008, they became Sleigh Bells -- a raucous, guitar-driven noise-pop outfit based around Miller's searing riffs and Krauss' baby doll vocals.

  • 6

    Phantogram

    Friends since junior high, Sarah Barthel (vocals, keyboards) and Josh Carter (vocals, guitars) formed the trip-hoppy Phantogram in 2007, but they didn't achieve mainstream notoriety until 2010 when 'When I'm Small' popped up everywhere on TV in commercials for Canon, Gillette and more. Their second album, 'Voices,' reached No. 11 on the Billboard 200.

  • 5

    The Knife

    Swedish siblings Karin Dreijer Andersson and Olof Dreijer began receiving international recognition for their electronic collaboration, the Knife, when an acoustic cover of their 2003 song 'Heartbeats' performed by Jose Gonzalez was used in a Sony commercial. Usually covering their faces with Venetian masks, the pair didn't perform live until 2006 -- and when they did, it was usually a massive, theatrical production. They announced in August 2014 they'll disband following their final tour in November.

  • 4

    Matt and Kim

    Real-life couple Matt Johnson (vocals/keyboards) and Kim Schifino (drums) started playing indie pop out of Brooklyn as Matt and Kim in 2004 and were put on the scene map after the viral success of their 2009 video for 'Lessons Learned,' featuring the pair stripping naked in Times Square. Fiercely DIY, they've since become festival favorites at the likes of Lollapalooza and Bonnaroo.

  • 3

    Beach House

    French-born singer Victoria Legrand and guitarist Alex Scally met in the Baltimore indie rock scene in 2004 after Legrand graduated from Vassar and created the dream pop duo, Beach House. After critics praised their self-titled 2006 debut, they've been on the forefront of the genre with their latest, 2012's 'Bloom,' already making best of the decade lists.

  • 2

    The Kills

    Back in the late '90s, American singer Alison Mosshart was touring Europe with her punk band, Discount, when she overheard British guitarist Jamie Hince practicing in his flat. They struck up a friendship and began sending musical ideas back and forth overseas until Mosshart moved to London, forming the Kills in 2000. With an early anti-industry stance and a darkly driving sound, they've cultivated a massive mystique on both sides of the pond.

  • 1

    The White Stripes

    Prior to the White Stripes' ascent out of Detroit during the early '00s, casual music listeners likely had no idea such a huge sound could come out of just two people. Dangerously charismatic frontman Jack White and his drummer "sister" (actually his wife from 1996 to 2000) Meg White played a brand of stripped down, lo-fi garage rock that leant itself both to intimate clubs and massive arenas. After six albums culminating in 2007's 'Icky Thump,' the pair went their separate ways with White going on to release two solo albums and a couple of records with the Dead Weather with none other than the KIlls' Alison Mosshart (among many, many other projects).

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