https://www.etzion.org.il/en/talmud/seder-nashim/massekhet-gittin/gittin-chapter-2-–-17a-introduction-divorce-way-get
In other words, either Gentiles do not need divorce, or they need divorce, but each party can divorce the other – the process can be initiated by either party, as opposed to divorce among Jews which depends exclusively on the husband.
The second opinion is that of Rabbi Yochanan of Tzipori who decides between these two possibilities and say that "To Israel have I given divorce, but I have not given divorce to the nations of the world."
The Rambam in Hilkhot Melakhim (9:8) spells out two ways to effect divorce among non-Jews:
When is a gentile woman considered divorced? When her husband removes her from his home and sends her on her own or when she leaves his domain and goes her own way. They have no written divorce proceedings.