It's not over 'til ...

Really, it's never over. My flatmate has a very on-again, off-again relationship. Every time she and her boyfriend break up, she swears to me that it's over for good (this time). It was the same story a few days ago ... but guess who I just saw in the kitchen? Oh, yes, the boyfriend is back! Why do people stay in such rocky relationships? Do they really like all that drama?