Question

Hello Rabbi,
 
There are tea bags that are sold in attached pairs, and before using them you have to separate them from each other by tearing at the designated spot. Is it permitted to do this on the Sabbath? Seemingly, this is not an issue of cutting to measure, because it does not matter that there be a precise cut, even though that is what happens in practice (like toilet paper). As for tearing, with food packaging it is usually permitted, as with palm-fiber baskets of dates, but here it is different: you cannot say that the packaging is nullified, because the goal is not to take the tea leaves out, but to separate the bag and use it.
 
What is the law?