A champion Ugandan boxer who has been living in New South Wales with his Australian partner and son is stranded in Thailand after attempting to qualify for the Olympics.

Regarn Simbwa took a risk to pursue his Olympic ambitions by going to Bangkok to compete in an Olympic qualifying event while waiting for a decision on his application for a partner visa.

"I was really worried taking this risk but this was a once in a lifetime opportunity," Mr Simbwa said.

The bridging visa he was on while waiting for a partner visa automatically ceased upon leaving the country.

His partner Elizabeth Dunlop, a lecturer at Charles Sturt University's Wagga campus, said they had hoped the partner visa would be approved before leaving for the competition.

Ms Dunlop said the uncertainty had taken a huge emotional toll on her family.

"The last four months have been very stressful, I've lost a lot of weight," she said.

"Before coming to Thailand was very, very stressful. 

"And I've been very upset, it's impacting on me at work.

Mr Simbwa lost his second round fight at the Bangkok tournament and failed to qualify.

The family was due to fly home on Tuesday. 

Ms Dunlop said she cancelled her flight home to have more time together, but said she must return to work on Monday.

She said she dreaded the prospect of leaving her partner behind with no indication as to when the visa processing would be finished.

"It's going to be really difficult going home without him, not only will I be caring for our son alone, he won't have his father, but then also taking on all the other burdens," she said.

"Paying all the bills, mortgage, childcare, going from a two income family to a single part time income, is just going to put huge financial pressure on."

Mr Simbwa said he hated the thought of saying goodbye to his partner and their son.

"It is going to be very hard being separated from Elizabeth and not being there for our son," he said.

"I would like to be their support, care for my family in all possible ways, and be a great dad to Matthew."

Couple met at church

Mr Simbwa was one of six Ugandan athletes who stayed in Australia after competing in the Commonwealth Games on the Gold Coast in 2018, living on various temporary visas while an application for permanent residency was being assessed.

"Back in 2018 I decided to stay in Australia as I was under a lot of pressure to help support my parents and siblings and couldn't get a decent job in Uganda," he said.

He met his now fiancee about three years ago at their church in Wagga Wagga.

The couple have a 14-month-old son.

"My life has changed completely from zero to 100 per cent since meeting Elizabeth," he said.

"I now have a loving, supportive and caring fiancee, and we have a beautiful son together."

He had been aiming to represent Australia in boxing at the Paris Olympics after beating the Australian champion in his weight division, but he said his application to secure permanent residency had stalled.

The couple got engaged in April last year shortly after the birth of their son and applied for a partner visa in June last year.

The department advises half of all partner visa applications are processed within six months, but the couple are still waiting.

'Overwhelming evidence'

While it was risky for Mr Simbwa to leave the country without a visa, Dr Dunlop said when Uganda offered him the chance to potentially go to the Olympics, it was a "once in a lifetime opportunity" they could not pass up.

So the young family went to Bangkok, where the Olympics qualifier for boxing started May 24.