The Gravity star's sister Gesine Bullock-Prado penned a touching message in honor of Bryan, who died on Aug. 5 at age 57.
"I'm convinced that Bry has found the best fishing spot in heaven," Gesine wrote on Instagram Aug. 7, "and is already casting his lure into rushing rivers teaming with salmon."
The pastry chef went on to note how Sandra, 59, helped care for Bryan during his illness.
"ALS is a cruel disease," Gesine continued, "but there is some comfort in knowing he had the best of caretakers in my amazing sister and the band of nurses she assembled who helped her look after him in their home. Rest in peace, Bryan."
On Aug. 7, Bryan's family shared that the photographer passed away after a three-year battle with amyotrophic lateral sclerosis (ALS), which he decided to keep private. ALS is a nervous system disease that causes loss of muscle control and worsens over time, according to the Mayo Clinic.
"Bryan chose early to keep his journey with ALS private and those of us who cared for him did our best to honor his request," the family said in a statement to People. "We are immensely grateful to the tireless doctors who navigated the landscape of this illness with us and to the astounding nurses who became our roommates, often sacrificing their own families to be with ours."
The family ended the statement with a message to supporters, adding, "At this time, we ask for privacy to grieve and to come to terms with the impossibility of saying goodbye to Bryan."
Sandra and Bryan's love story traced back to 2015, when the actress hired him to photograph her son Louis' fifth birthday party. Less than a year later, a source told E! News that Bryan—a former model—was living "with Sandra full time" and that "they have been spending most of their time together."
"His whole life had been unraveled because of me," she said during a 2021 appearance on Red Table Talk, "He was so happy, but he was scared. I'm a bulldozer. My life was already on the track and here's this beautiful human being who doesn't want anything to do with my life, but [is] the right human being to be there."
Calling Bryan "the love of my life," Sandra explained that he was "the example I would want my children to have."
"I don't always agree with him and he doesn't always agree with me," she added, "but he is an example even when I don't agree with him."
And, no, she didn't need a wedding ceremony to validate their relationship. As she explained, "I don't need a paper to be a devoted partner and devoted mother."