Frankly, I'm surprised there haven't been more blowups.
You take a bunch of strangers, and you put them in a cramped house, where they're stuck together 24x7 (normal BB).
Then you add the couples twist, where some loose cannon that you have no control over is having an immediate impact on your ability to win $500,000. And you know all the psychological testing they do before hand had to figure in to the pairings - by determining which person is most likely to irritate the hell out of who, and partner them together.