I've seen 'MMF' pop up in fan discussions a lot, especially in romance-focused communities. It typically stands for 'Male/Male/Female,' describing a polyamorous or romantic relationship dynamic involving two men and one woman. This term is common in fanfiction, erotica, and certain romance subgenres where multi-partner relationships are explored. I first encountered it in tags for stories on platforms like Archive of Our Own, where readers use it to filter content. It's not just limited to written works—some visual novels and dating sims, like 'Room No. 9,' feature MMF dynamics. The term helps audiences find specific relationship structures they enjoy without confusion.