When you think about it, the world of Hollywood is really quite small. It's therefore pretty unsurprising that actors and actresses working on the same projects sometimes end up dating the same person. While it may happen more often than you might think, it never gets any less awkward.
Here are seven co-star pairings who broke all the rules and did the dirty with the same person.
1. Nikki Reed & Kristen Stewart
Who did they date? Robert Pattinson
Before R-Patz was doing it with K-Stew, he actually dated fellow vamp and Cullen family member Nikki for a few months in 2009. Awks.
2. Jamie Campbell Bower & Taylor Lautner
Who did they date? Lily Collins
Taylor Lautner dated Lily Collins after meeting her on the set of Abduction in 2010. Sadly, they split up just a week before the movie premiered, making for rather awkward interactions on the red carpet. Later, Taylor went on to work with Jamie Campbell Bower on Twilight, who began dating Lily soon after. Let's just hope there's no bad blood there now!
3. Robert Pattinson & Kristen Stewart
Who did they date? Soko
Well isn't this great. Before these two lovebirds broke all of our Bella and Edward hopes and dreams when they tragically split, Rob actually went on a blind date with artist Soko. And guess what? She's currently K-Stew's GF.
Oh, how things change!
4. Selena Gomez & Miley Cyrus
Who did they date? Nick Jonas
Disney sweethearts Selena and Miley both dated Nick Jonas. Way before she was twerking in a nude-colored thong all over an MTV podium, she dated the Jonas brother in 2006, before breaking up in 2007. A year later and his new girlfriend was Selena, who he was with on-and-off until 2010.
5. Topher Grace & Chris Masterson
Who did they date? Laura Prepon
At one point both Topher Grace and Chris Masterson starred on That '70s Show and at one point, both of them dated co-star Laura Prepon.
6. Nikki Reed & Ashley Greene
Who did they date? Ryan Phillippe
Yep, it seems that there's something a bit incestuous going on within the Twilight cast. On-screen sisters Nikki and Ashley were both involved with Ryan Phillippe. Nikki in 2007, way before she married her husband Ian Somerhalder, and Ashley later in 2013.
7. Ashley Benson & Lindsey Shaw
Who did they date? Devon Werkheiser
These two didn't only share on-screen time on Pretty Little Liars — they also both got hot and heavy with Devon Werkheiser. Meow!
Which co-stars surprised you the most?