It is very much possible if both of them (the platonic friends) are clear in their intentions, subject to understanding and the maturity of their respective partners about their partners and about their partners friend and friendship. Very rare possibility though. You know fear breeds insecurity and so does greed breeds insufficiency.
Although the views of
@Endorphin is very pertinent and valid, one of their being beautiful makes it more remote as fear and greed grows disproportionately w.r.t beauty of another person, I have observed even the not-so-good-looking man and girls friendship was frowned upon by family, closer circle and larger circle. Pity.