Robert Pattinson and Kristen Stewart - Are they or aren't they? It's a conundrum that fascinates millions of Twilight fans across the globe, and not one the rumoured couple are in any hurry to clear up.
With work commitments keeping both the stars from Thursday night's Eclipse premiere in London, there was no chance to see the pair together on the red carpet. No opportunity to check out the body language which might give clues as to their relationship status.
When they met, during auditions for the first Twilight film, the film's director Catherine Hardwicke noted their instant chemistry. The pair became close during the subsequent filming of the movie, but Kristen was dating another actor, Michael Angarano.
By the time the pair were promoting the film, that relationship was over, and the buzz had already started that Robert and Kristen had taken their on-screen love story across into real life.
Kristen has said in no uncertain terms that she "would never cheapen my relationships by talking about them". Though she has spoken about her affection for and closeness to Rob in the past.
"He's a hunk, the sort of guy that makes any girl feel good. He's intelligent, he's modest, and - whatever else people say about our relationship - he's my best friend."
He too has been equally descriptive about the depth of their friendship.
"When we're together, we understand each other very well,' says the 24-year-old. "We know what each other is thinking and we have been very close for a long time. Kristen is a wonderful girl."
It's hardly surprising that the pair have become so close. They're living a unique experience which no-one else can lay claim to. Going from being relatively unknown - through the medium of Twilight - to the dizzy heights of mega fame.
And both seem equally unenamored by their new uber star status, especially Kristen. The 20-year-old told Elle magazine that when she's on the red carpet, "I literally, sometimes, have to keep myself from crying."
Rob says himself that: "Kristen and I have lived a great adventure together with the Twilight films. We are very close and no one can understand what we've gone through together the last few years."
Despite this incredible bond the pair share, they're rarely seen out in public together. When Kristen did turn up to the premiere of the British star's film Remember Me, she was very careful not to be photographed with him.
Even at the Twilight premieres she's most often seen posing with Taylor Lautner, and telling interviewers how much she likes him.
Perhaps Robert and Kristen have merely come to the conclusion that their lives will be a lot easier if they opt out of feeding the fan's hysteria – their relationship will be better conducted in secret, behind closed doors.
"It's extremely difficult when we are out together,' he said when they appeared at this year's Baftas.
"We can't arrive anywhere at the same time because the fans go crazy. This was supposed to be a public appearance as a couple, but it's impossible. We are here together and it's a public event, but it's not easy."
Whether or not they turn out to be the next Angelina Jolie and Brad Pitt remains to be seen. For now Robert and Kristen are keeping their love firmly under wraps.