How is it that some people constantly find new romantic partners so quickly?

I was reading a bit of blind item gossip on Gawker today about how this (former) Hollywood couple made nicey-nice while sitting together at the Oscars. However, in real life they can’t stand each other and had actually broken up a little while ago, though the public thinks they’re still an item. The gossiper added that they each found new boyfriends very quickly after their breakup a few months back.

How does that work? It takes a lot (and some time) for me to deign a man my boyfriend. Otherwise, we’re just dating/hanging out, you know? I have known people who’ve broken up with “Mike”/“Tracy” on Monday and introduce “Sheila”/“Phil” on Wednesday. To me, finding a sexual partner, or a dozen, even, that I can understand; just troll a bar tonight and ask, “Yo, who’s up for it?” But a boyfriend? Or girlfriend, if that’s your flavour? How does one get into a new emotionally intimate relationship just like ::SNAP!:: that?

Or am I not understanding something important about such relationships?