The 5-year-old boy was diagnosed with leukemia on Nov. 17, and has since been in and out of Rady Children's Hospital in San Diego.
"She just spoils him with attention and Legos. She really knows the way to his heart," Sosy Robinson, Gideon's mom, told TODAY. "Even if she's not assigned to his room, she'll come and bring him Legos."
On Jan. 27, he made his bride-to-be a ring out out of pink and white pipe cleaners with a heart-shaped purple plastic stone, and even created a box out of construction paper.
When the time finally came, the hospital's music therapist, Emma, played Gideon's favorite song, "Happy" by Pharrell Williams, while about 20 people gathered to witness the toddler get down on one knee.
"It was really, really cute and sweet," Richardson told TODAY.com. "I was surprised by the amount of people he got to come."
Richardson, of course, said yes and even called him her "hospital husband."
"He was so excited, running around all day telling everyone he was marrying Sarah," Robinson said. "He was very anxious for 3 p.m. to come around."
When the time finally came, the hospital's music therapist, Emma, played Gideon's favorite song, "Happy" by Pharrell Williams, while about 20 people gathered to witness the toddler get down on one knee.
"It was really, really cute and sweet," Richardson told TODAY.com. "I was surprised by the amount of people he got to come."
Richardson, of course, said yes and even called him her "hospital husband."
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"We didn't expect for her to be so touched by Gideon's proposal," Robinson said. "We were just making a cute memory together, but didn't think it would be as special of a moment for her as it was for us."