What is the ruling on an infertility consultant working in Western countries, and is it permissible for him to treat two unmarried individuals, or to treat non-Muslims using sperm, eggs, or embryos from donors?

Previously, artificial insemination was considered forbidden due to the potential for lineage confusion, except in two cases: First, if the sperm is taken from the husband and the ovum from his wife, and fertilization occurs externally, then the embryo is implanted in the wife's womb. Second, if the husband's sperm is taken and injected into the appropriate place in his wife's vagina or uterus through internal insemination. In these two cases, there is no difference whether the treating physicians are Muslims or non-Muslims. As for the treatment of infertility for unmarried individuals, if the intention is an illicit relationship between them, then it is not permissible. However, if the intention is to treat those who are preparing for a legitimate relationship, such as marriage, then there is no objection.