When i saw that series(and discription) at first i was like "Meh, another school-harem, i think i'll skip it." And then... Tension grew larger from ep to ep. OMFGWTF I was so shocked. But that's how it must be done in RL-like anime i guess. :)
It happens occasionally, sure, but it's incredibly rare. It just seems more common because when it does happen, it's all over the news (because, again, it's so rare).