Love Triangle Subtrope?

So I was thinking about Love Triangles the other day, particularly in the "Both B and C love A" variety. But then I starting thinking—what if one of the ways to resolve the triangle was having B and C fall in love with each other. This way the love triangle is resolved by having A become a third person with B and C having a relationship together.

Simply, an B—>A<—C triangle is resolved by removing the "A" altogether: B—><—C.

Alternatively, it can become more complicated if it starts off with B—>A<—C if it ends up being A—>B<—C, where a different member of the triangle becomes the focus. I'm not counting an ABC arrangement because that would be like OT3 or the Harem option, depending how you see it.

Anyhoo, does this subtrope already exist? If so, what's it called? In what media does it appear in?

You might want to try Trope Finder for this inquiry, although if it is sufficiently uncommon, there won't be enough examples to make a good trope.