'Golden Bachelor' Gerry Turner's Cancer Diagnosis Major Factor in Theresa Nist Split

Gerry Turner is finally sharing more about his surprising split from Theresa Nist, who he married on the 'Golden Bachelor' ... and it turns out a cancer diagnosis played a major role.

Gary and Theresa got hitched shortly after getting engaged during the inaugural season of the new spin on the popular dating show, which aired in November 2023 ... but a mere 3 months after the big wedding, it was splitsville.

In an interview with People, GT revealed that after tying the knot, he was diagnosed with a slow-growing "bone marrow cancer" ... called Waldenström's macroglobulinemia.

In addition to the stress and worry about the battle ahead ... the couple was having issues when it came to figuring out other life logistics, like where they would live ... but that was all a secondary factor to the diagnosis.

Long story short ... after the jarring news, Gary wanted his life to "continue on as normal as possible, and that led me to believing that as normal as possible more meant spending time with my family, my two daughters, my two son-in-laws, my granddaughters."

And that decision meant Theresa would need to take a backseat in his life ... which ain't conducive to a successful marriage -- especially one just getting off the ground -- so they called it quits.

Noting that he wished Theresa all the best ... he plans on living life as full as possible, meaning ... "pack as much fun as I possibly can into my life and enjoy every moment. And when I'm gone, I'm gone, but I'm not going to have regrets."