Morgan Carberry, 31, was looking forward to being able finally to apply for permanent residency after making a home in Scotland for nearly 10 years.
But just weeks before the date when she could apply, her partner suddenly left her - meaning she was no longer eligible to stay on her 'spouse/partner' visa and apply for indefinite leave under rules which allow an application to be made after 10 years of being in the UK.
Just last Friday Carberry was invited by Salmond to sing at an event in Edinburgh Castle for a Chinese trade delegation.
With her leave to stay due to expire by next Saturday, Carberry has now reluctantly booked a flight back to the US on Tuesday, with her only hope resting in a plea from Salmond on her behalf for "ministerial discretion" from Immigration Minister James Brokenshire.
Carberry first came to Scotland as a postgraduate student on a prestigious Marshall Scholarship from the British Government.
She then obtained a post-study work visa as a result of the Scottish Government's "Fresh Talent" initiative, which encouraged foreign nationals to settle in Scotland.
She stayed on using a general visa, before deciding to switch to a spouse/partner visa as it was a "faster, simpler and less expensive route" to permanent residency, which she was due to be able to apply for on June 9.
Carberry said: "Literally out of the blue, about two weeks before the first date I could apply for clearance, my partner left me. There was not a hint of a problem in the relationship."
Following advice from lawyers, she decided against applying for discretionary leave from the Home Office after being advised the rules means the case would be unlikely to succeed.
She said: "I have every faith that I will come back to Scotland and the UK one day as I have built such a network of personal and professional connections here. That is why I made the very difficult decision to book a flight with only a few weeks' notice and go back to the US."
Carberry said performing the song Caledonia at Edinburgh Castle had been poignant as she knew she had to leave the country in days.
The letter sent by Salmond to UK Immigration minister James Brokenshire notes it was only the "unfortunate breakdown of her relationship" that prevented her from applying for permanent residency and that she would have qualified earlier for applying for indefinite leave to remain in the UK, but for a return to the US as part of her scholarship.
The letter urges Brokenshire to consider granting discretionary leave to Carberry or immediately granting indefinite leave to remain given "the compelling nature of her commitment to the culture, community and economy of Scotland".
The Home Office said it could not comment if an application had for leave had not been made.