The Rolling Stones rocker - who has an estimated wealth of around £200 million - was said to be ''hugely supportive'' of his late partner, who was found dead in an apparent suicide on Monday (17.03.14), and did his best to get her fashion label out of debt.
However, L'Wren - who hanged herself in her New York apartment - was ''embarrassed by what had happened'' financially.
A source told the Daily Mirror newspaper: ''L'Wren was left terribly upset by what was going wrong with her business, none more so than when she was forced to cancel her London Fashion Week show in February.
''She was a proud woman and understandably embarrassed by what had happened. While Mick was there for her every step of the way trying to help out as best he could, the situation must have put pressure on their relationship.''
L'Wren was forced to cancel her London Fashion Week show in January saying at the time fabrics arrived too late for samples to be sewn for the event.
However, insiders claim she made the decision to mask her huge financial problems, with accounts filed for her business LS Fashion LTD in October 2013 showing a deficit of £3,546,000 and the designer owing creditors £4,593,000.
The friend said: ''She blamed the fashion week debacle on production delays but this was masking the huge financial problems her company had.
''In the cut-throat world of fashion, reputation is everything and it must have been a huge personal blow to pull the show. Her fear of failure in her peers' eyes may, ultimately, have been too much.''
Jo Wood, the ex-wife of Mick's Rolling Stones bandmate Ronnie Wood, said she believes L'Wren's financial situation was the final straw for her.
She told CNN: ''Well, maybe, if anything the financial thing might have been the trigger, because she was such a proud woman that I think to face that, well maybe that was the trigger. I don't actually know, I'm surprised as much as everyone else.''
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