“Each conscience seeks the death of the other" - Hegel
She Came To Stay by Simone de Beauvoir uses the love triangle to explore the philosophical concept of The Other. People, maybe especially feminists, seem to find it annoying. The main character, Francoise, loses her mind when her partner, Pierre, falls for Francoise's attractive young student Xavierre, even though Francoise and Pierre are in a committed open relationship. The self-destructive romantic obsession Francoise experiences as a result is described in horrible detail. There is no happy ending. Confession: I've read it three or four times already and I'm sure I will again.