Aplatonic, abbreviated Apl (pronounced as "apple") is a term that is used most commonly by a-spec individuals that do not experience platonic attraction or by those who do not relate to the concept of platonic love.
The term has also been used by neurodivergent aromantics (particularly those with a schizophrenia spectrum disorders) and traumatized aro people, who might not desire friendship or other platonic relationships.
Aplatonic does not refer to someone who simply "doesn't have friends" or "doesn't want friends", rather it describes someone who does not experience "platonic crushes" or "squishes" like some a-spec people do. Some aplatonic people may still have strong platonic bonds (though not all desire strong platonic relationships), however they never experience a strong desire to be friends with someone in particular, or feel as though the term "love" can be applied to the relationship.
The term aplatonic was first introduced by a homoromantic asexual on the AVEN forums. In his words, "I have friends and care about them; but love is a powerful word, and one I cannot apply to them."
The earliest remaining record of the purple, blue, and green aplatonic flag is from the DeviantArt page Pride-Flag on August 17, 2015. It seems that the flag existed before then, but any evidence of its creation no longer exists. The colors are the inverse of yellow, pink, and brown, colors that are typically used to represent friendship. White represents how an aplatonic people can still be allosexual/alloromantic, a reference to the white stripe on the asexual and aromantic flags. Cream was used instead of pure white to make the flag more visually appealing.
The yellow aplatonic flag was created by the Tumblr user Pride-Color-Schemes on June 26, 2016. The black, grey, and white stripes match that of the asexual and aromantic flags. Yellow is used to symbolize the platonic/aplatonic spectrum.