Okay, okay…not always! I'm also talking books here people. Even beyond books via movies and television shows. It's a fact of life, it happens; and creates much needed drama sometimes. It's an out, or a meaty way of adding a bit of something to you're writing.
Why do people hate them so much? Maybe because it is unrealistic (most of the time), and you want to see your favorite couple live happily without interference, but sometimes it not only creates drama, but a much needed clarification for couples. It is a hurdle they must overcome and a test to see if some are meant to be. I also think it is because as a reader or watcher you can root for a certain couple only to find that your couple were not the couple the author thought of. It can rear the emotional aspect if the reader is invested and possibly turn them off to the series entirely.
Yet, there is also the possibility that the reader will watch or read until the end of the series to truly see who they end up with; I've also seen books were the author wrote to versions showing what would happen if the triangle went both ways. It gives a clearer picture sometimes of why the author chose to go one way.
Although, of course, there are those moments when a triangle is completely unnecessary and should remain a line without other lines veering into it.
What are your thoughts on the subject?