The last two movies I saw in theaters (Cloverfield and The Spiderwick Chronicles) had this cliche. It annoyed me in Cloverfield, but I let it roll off. It really bugged me in TSC.
The thing that's mysterious about this particular cliche is that there's no real reason for it. If you left it out, it would have no effect on the plot whatsoever.
Even if a boyfriend and girlfriend have a fight earlier or even if a parent and a child have a fight, it's still believable that they'd want to save each other later if one discovers the other is in danger. You may get angry at someone, maybe even enough to say you hate them, but that doesn't mean you want them to get killed by a monster.





