The email from Nicole Scherzinger's agent arrived the morning that we were due to meet: "Nicole does not discuss her relationship with Lewis in interviews."
It sets alarm bells ringing, because in every interview the Pussycat Doll-turned-West-End-star has given recently, she has talked about her seven-year romance with British F1 champion Lewis Hamilton.
She has described him as an "alpha male", "the most competitive person I know". In a rare interview in December, he dubbed her "inspiring" and "a hard worker".
On Wednesday, however, it was reported that the 36-year-old former X Factor judge and Hamilton had broken up over his refusal to settle down with her.
It is the fourth time the couple have split during their relationship, which was always rocky and fraught under the strain of long-distance romance (Hamilton is based in Monaco, Scherzinger in Los Angeles).
Their first break-up came in 2010, three years after they met on the red carpet at the European Music Awards, with their spokesmen insisting they wanted to "focus fully on their careers". Then, almost as quickly as it had ended, things were back on again: she called him her soulmate; he said he was like a "besotted schoolboy".
In 2011, they split again, closely followed by a reunion and rumours that they were engaged (they weren't). In 2013, Scherzinger turned down an actual proposal, leaving heartbroken Hamilton, 30, with a €500k credit note at the Cartier store in London's New Bond Street. Things were off, then on again. As recently as last weekend, Hamilton is said to have dusted off that credit note, asking staff at the jewellers to prepare their "top three" engagement rings for inspection, sparking reports that a proposal was back on the cards.
Now it seems that the "Ham-zinger" power duo have broken up for good.
"It really is over this time," a source said. "Nicole has finally had enough. She's completely gutted and feels lost about her future."
Suddenly, our oddly emotional encounter makes a lot more sense.
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I met Scherzinger after a sold-out matinee performance of Andrew Lloyd Webber's celebrated musical, Cats, in which she plays Grizabella, the "glamour cat" fallen from grace, who is taunted by her fellow moggies before finally finding redemption. Her performance is electrifying; her rendition of Memory, the Puccini-esque headline number sung in the original by Elaine Paige, breathtaking. Audience members are on their feet; a woman next to me is sobbing.
Such is the demand for tickets that the musical has been extended by two months until the end of April. Scherzinger, treading the boards since December, will sing her last song this Saturday.
On this side of the Atlantic, we know her best for those barely there outfits in girl band the Pussycat Dolls and her perky turn of phrase as a judge on The X Factor, but Scherzinger says musicals are her first love. She speaks languidly, dreamily, in an unfathomably high octave, and she is slumped on a sofa in her softly lit dressing room, stage make-up caked around bloodshot eyes. She looks like a broken - or, indeed, heartbroken - doll.
"She is the Marilyn of Monroes," she is telling me. "Grizabella gives her last breath on that stage. I don't know if I would be able to do six months to a year like other people do, because every night is so raw. I feel like I'm becoming her. Grizabella and Nicole are one." She sighs dramatically, heaving her tiny shoulders. "It's exhausting because you have to give everything. Twice I've fallen to my knees because I have nothing left to give. Every performance, I feel like I die on stage and that's quite emotional."
Tears shine under her huge false eyelashes, and it takes hefty self-restraint not to lean over and give her a hug. Scherzinger seems far younger than her years.
She was pictured earlier this week with her mother, Rosemary, and beloved grandmother, whom she flew over from Hawaii to watch her perform - and, it now emerges, for some much-needed support.
"I try not to regret things, because I feel like as long as you put positive energy towards something - and you put your whole self, your true self, towards it - it'll lead you to the next place you're supposed to be," she says. "I look at this as a great blessing for me to be able to take on this role…but I have made sacrifices. This is very time-consuming. I've left LA, left all my friends and my family. It's sacrificing your time in relationships, with loved ones, and my work."
She was born Nicole Elikolani Prescovia Valiente in Honolulu, Hawaii, to a teenage Hawaiian-Russian mother and a Filipino father, Alfonso, who walked out when she was two. Four years later, she moved to Louisville, Kentucky, with her mother, German-American stepfather Gary Scherzinger and younger sister Keala. It was a difficult upbringing; no money, second-hand clothes, bullied at school.
She grew up in a religious family - her grandfather was a pastor, and she is a staunch Catholic, praying before every appearance - and her mother famously cried when she saw the raunchy clothes her daughter would be wearing in the Pussycat Dolls. She joined in 2003, and the group went on to sell 54 million records. But Scherzinger's time with them was troubled.
"I was young enough and hungry enough that I wasn't too wrapped up in anything," she insists. "But it went by so fast and I didn't really get to fully take it all in. I was too dead-set thinking of work."
She hopes, by the time she returns to the US next week, to "have made her mark on the West End".
But her break-up with Hamilton has thrown plans further ahead into disarray. Where does she hope to be 10 years from now? "Geez," she breathes, through gritted teeth. "I was supposed to do a vision board and ask myself that, but I haven't got round to it yet. I'll be around 45 [46, actually, but I don't correct her], I want to be looking good. Gosh, that's intense. I don't know, maybe have had some movies under my belt, more albums, travelling the world, world tours would have been beautiful… having done a lot of good charity work."
What about marriage and kids, I dare to ask, are they in her plan? "Oh yeah, I'll definitely have that by then," she nods, furiously. "I'll definitely have that. Definitely, that would be nice." She tails off, and swiftly changes the subject.
For now, this pussycat is keeping her claws very closely sheathed.