L'Wren Scott was desperate to have children, her estranged sister believes, and was struggling with some serious financial problems before taking her own life.
Jan Shane, 53, wonders if that void and longing for a family, rather than money woes or a non-breakup with Mick Jagger, might have led to her suicide.
Jan Shane, who hadn't spoken to her famous adopted sister in years, and her husband Rob Shane, said Mick Jagger offered to pay off her mounting debts.
L'Wren, born Luann, was "too proud" to accept his help, despite the Rolling Stones frontman's incredible wealth and their romance of more than 10 years.
However, the couple don't believe the $6 million L'Wren's crumbling business owed to creditors would have driven her to suicide. But a deep longing for kids?
"I know deep down she wanted a family and kids, and I think she deeply wanted it and couldn't get it. I think it bothered her," Jan, who has eight, says.
Jan revealed that years ago, at their father Ivan's funeral, L'Wren Scott arrived flaked by bodyguards and told her she envied her quiet life in Utah.
"It was hard to get near her. I don't know why she thought she needed bodyguards at our father's funeral. I guess that's just how her life was at the time."
"At one point we stepped out together and she looked at me and said, 'I envy you.'"
"She had her career and her company and everything - she'd made it. I looked at her life I didn't believe what she was saying and she told me, 'You have your family.'"
She "always thought (a family) would be part of her life at some point, but she had this dream of being this famous model, designer to the stars, to Michelle Obama."
"Now it was like 'I've done what I want to do, and now I want to start a family.'"
The 49-year-old was found dead in her apartment in Manhattan's Chelsea neighborhood Monday morning, leaving Jagger struggling to understand why.
She had hanged herself while the Rolling Stones frontman was in Australia, leaving him "shocked and devastated" and canceling the band's tour dates.
Jan said she learned of L'Wren's death after a friend send her a text, showing the level to which their relationship had deteriorated over the years.
However, she spoke very fondly of her younger sister and said she wished they had been closer but their lives were so starkly different, lately in particular.
Jan described L'Wren as "a very private person' who never let on if there was something wrong, rather "all we saw when she was home was a super-strong woman."
"They don't see the other side of her and she isn't going to tell you," she said, adding that she wished she could have done something to help her sister in need.