The people involved do not have to identify as "queer", it's a type of relationship experienced by and available to anybody regardless of their sexual orientation, romantic orientation, or (non-)monogamy. The people involved in a queerplatonic relationship may consider themselves partners, life-partners, a couple, a triad, or any other term that implies the relationship is meaningful, committed and intimate.
Quuerplatonic parters or QPs are sometimes referred to as "zucchini". As in, "he's my zucchini". This was originally a joke within the asexual/aromantic community, underscoring the lack of words in mainstream relationship discourse to signify meaningful relationships that do not follow the standard and expected sexual/romantic norms, and frustration with the erasure of other kinds of intimacy, which were perceived as equally valuable to the sexual/romantic model.
I never understood why people were so opposed to affection of any kind towards people that are not dating, I think the world would be better if everybody could cuddle and it was not weird (kind of like how it used to be in Abe Lincoln's time when it was normal for men to sleep in the same bed together as a strictly platonic thing or like queerplatonic relationships maybe).
They told their friend about queerplatonic partnerships the same day they asked their friend if they could be queerplatonic partners, and they said yes.