Best friends are those who detect when you need a good hug. They spot you from a distance, you look into each other’s eyes, and communicate telepathically. You walk towards each other and there’s no need for words. You have already agreed to hug without saying anything. This ideal friendship is what these two gibbons seem to have.
According to a commenter on the Reddit thread where the link was posted, white-cheeked gibbons are indeed as sweet as they look. “They are monogamous [socially, not sexually] and both mom (white) and dad (black) care equally for the young. The babies are born white no matter the gender, so they can blend in with mom. Later, they all turn black and hang out with dad more. When they reach sexual maturity, the females turn white again.” Should we turn to gibbons to learn about equality? Other commenter adds “gibbon families sing songs together to help define their home territory.” I know you were going to look for it, so here’s their Wikipedia entry for you. Enjoy.