Before anyone suggests making one, just crossposting to inform other people that this idea came from the Three Amigos Wick Check I've started at the project thread.
Working on: Author Appeal | Sandbox | Troper WallIn my opinion, without seeing any results so far and based on vague memories of reading books with a dynamic that I would identify with this, I would say that the romance between the main character and the opposite gender friend is at least implied. I wouldn't say that the two characters were guaranteed to go on a date, and this is at least partly due to the ages that I associate the dynamic with; preteen and tweens.
In a one-book story, the romance angle isn't always explored. However, likelihood that the two will try some sort of couples activity increases as the series goes on. I don't think that I'd insist that every example would require mention of what couple activity two of the characters engage in, which implies that the romance angle is not needed for context.
I think the romance is implied because much of European-derived culture (such as America) puts an unhealthy emphasis on an "opposite gender relationships are based on sex" concept. I don't think we generally do a good job of presenting healthy boy-girl relationships that ignore the romance angle. Tamora Pierce is an exception to that, compared to other writers. It probably shouldn't be a component of the Three Amigos by itself, it's another trope of boy-girl relationships that is overlapping with that one because it includes a boy-girl relationship.
EDIT: It should still go through TRS, but I think rewriting should focus on the "Any romance is secondary.", which ironically contrasts with "There will be romance.".
Edited by crazysamaritan on Apr 4th 2022 at 9:48:45 AM
Link to TRS threads in project mode here.I think you've got the right of it.
This seems related to Two Guys and a Girl (which from the description seems like a sub-trope). The description puts a lot of emphasis on the two male characters coming into conflict, usually over the affections of the female character. But the examples most examples don't actually feature this, and are just literally "a friend group consists of two guys and one girl,"
Edited by TheMountainKing on Apr 5th 2022 at 4:34:34 AM

Three Amigos says one of the characters is
- A best friend of another gender, and potential Love Interest, 50% of the time an Unlucky Childhood Friend. She (or he if the protagonist is female) is frequently the Betty on a Betty and Veronica love triangle.
and