Marwa Omara said it was "a very hard" decision for Mohamed Fahmy.
"He is a proud Egyptian that comes from a family of military servicemen," Omara said in an email to The Canadian Press.
"They told him: 'Nationality is in the heart, and you can come in as a tourist'."
It remained unclear when exactly Fahmy would be released.
However, Foreign Affairs Minister John Baird told CBC on Monday that Fahmy's release was "imminent." He declined to provide any more details.The 40-year-old was expected to be deported to Canada when released.
Fahmy's brother, Adel Fahmy, said Tuesday that many of their family members in Egypt are offended and upset at Mohamed for dropping his nationality and don't want to even say goodbye to him.
Adel Fahmy said his brother was devastated but both his fiancee and his mother told him to do it.
Fahmy's mother sent a public letter to Egypt's president on the weekend, calling her son an "innocent" man in urgent need of medical treatment.
"Mr. President, as a journalist my son never strived to tarnish Egypt's image. It's this Al Jazeera case that now smears Egypt's reputation abroad," wrote Wafa Abdel Hamid Bassiouni.
Fahmy and two Al Jazeera colleagues — Australian journalist Peter Greste and Egyptian Baher Mohamed — were arrested in December 2013 and convicted of terror charges related to their coverage of the violent crackdown on Islamist protests. They were sentenced to between seven and 10 years.
Their trial sparked condemnation from human rights and media groups around the world.
Greste was finally freed on Sunday. In his first public comments since his release, Greste told Al Jazeera English that he experienced a "real mix of emotions" when he was freed because his colleagues remained in prison.
"It was a very difficult moment walking out of that prison, saying goodbye to the guys, not knowing how much longer they all have to put up with this," he said.
Greste said his freedom was something of a "rebirth" and that the key to his well-being while incarcerated was exercising, studying and meditating.
Prison officials and Egypt's official Middle East News Agency said Greste's release resulted from a "presidential approval" and was co-ordinated with the Australian embassy.
Egyptian authorities had accused the three journalists of providing a platform for ousted president Mohammed Morsi's Muslim Brotherhood, now declared a terrorist organization. But authorities provided no concrete evidence.
The three were widely seen as having been caught up in a regional power struggle between Egypt and Qatar, which funds Al Jazeera and had been a strong Morsi backer.
The journalists and their supporters insisted they were simply doing their jobs during a time of violent upheaval.
— By Colin Perkel in Toronto.
—With files from The Associated Press
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