When a momma gorilla and a papa gorilla love each other very much... (and significant resources are dedicated to keeping them safe, content and ready to procreate, which is what I'm assuming Reddit has achieved.)
But yeah, basically it's love.
[0]https://www.youtube.com/watch?v=3431b8twU-U
[1]https://pubmed.ncbi.nlm.nih.gov/19399838/
[2]https://pubmed.ncbi.nlm.nih.gov/19722225/
[3]https://www.youtube.com/watch?v=JOtDSysn2kA
[4]https://qz.com/1484989/male-gorillas-who-care-for-infants-ha...
Okay, I only giggled at the first one, but I laughed at this one.