Rebecca Palmer, 26, from Royal Wootton Bassett, Swindon, Wiltshire, made a series of false allegations after the victim told her he wanted nothing to do with her.
London's Court of Appeal heard on Thursday that she made his life a "living hell" with a series of lies and abusive messages, and continued to lie to police after her deception was uncovered.
Palmer was found guilty at Winchester Crown Court of four counts of perverting the course of justice and admitted five further counts.
She also admitted five counts of sending malicious communications.
Her lawyers argued that her five-year jail term was "excessive" and did not take enough account of her "significant mental health difficulties".
The court heard that she suffered a brain injury at the age of 10 after being kicked in the head by a horse, and also had personality disorders.
But her appeal was rejected by three senior judges, who said there was "nothing wrong" with the sentence.
Mrs Justice Andrews told the court that the victim's rejection of Palmer in 2015 "unleashed a storm" of false accusations - including of rape, fraud, blackmail and violence.
The victim, a serving soldier with the King's Royal Hussars, based in Tidworth, who was 20 at the time, was arrested, questioned and detained for more than 19 hours.
After he was released on bail, Palmer continued to lie to police by claiming he was contacting her in breach of his bail conditions and was stalking and harassing her.
She also used false identities to send abusive messages to his mother and her friends.
Her lies were eventually discovered following a "thorough" police investigation, but she continued to insist she had been raped and make false accusations.
The Crown Court judge said her false complaints had wasted "vital" police time and resources in Wiltshire.
Rejecting her appeal, Mrs Justice Andrews said: "For offending of this seriousness there was nothing wrong with the length of the sentence passed."
The judge, sitting with Lady Justice Sharp and Judge Peter Collier QC, said that, were it not for Palmer's mental health problems, she could have expected a sentence "in excess of" five years.
She added: "Despite those difficulties, it was very clear that there was a degree of pre-planning in her offending and that she knew that she was lying."
The judge said Palmer's campaign against the victim was designed to cause "maximum damage" to him and she was prepared to lie even after being caught out.