1. Death in the family, Death of a loved one
2. Getting rejected
Other than that, what came up was "liking someone and then finding out that she/he is taken" - YON! Hahahaha. That absolutely sucks. Why? Because you have to make a decision. To wait it out or not. What if you wait for nothing? It makes it more interesting though... You have certain personalities that say "mas madaling hulihin ang manok na nakatali" (it's easier to catch a chicken that's tied down)
But that's not honorable... No integrity and respect either.
It only makes life more interesting right?
I guess you just have to enjoy the ride.