Imagine two friends A and B.
A: Hey, want to go to this Indian place?
B: Nah, I don't really like Indian, how about this Mexican place?
A: You don't like Indian food? How is that possible?
B: I don't know, I'm just not a big fan. And you always want to go to an Indian place, why do you like it so much?
etc
At about line 3, it changed from a conversation about "where to go for dinner tonight" into one about "whether Indian food is good". That's probably not the one you need to solve.
Put another way, imagine the restaurants A likes as one circle, and the restaurants B likes as another one. A and B are trying to force those circles to overlap completely. But that's not the right question - the question is "can we find one place that's in the Venn diagram overlap between A and B?"
These also come up when you're thinking about the future ("what will we do if ____"). You've both got a decision tree in your mind, and you want those trees to overlap perfectly, but you don't really that at all. You just need them to overlap for the part of the future that ends up coming true. So maybe it's not worth arguing about the low-probability branches of the decision tree, and instead focus on stuff that's either true right now or is more likely to be true in the future.
Anyway, just keep your eye out to notice when you're dealing with a Venn diagram problem.
