This is the meanest reason to break up with someone

Rejection hurts. But it stings even more when you're turned down for another person: dumped because your partner found someone better, for example, or passed over for a great job because of a more qualified candidate.

That’s the finding of a new Cornell University study, published in Personality and Social
 Psychology Bulletin, that took a close look at two types of rejection. In one type, someone else was chosen instead.