Analogy for monogamy

Imagine you're craving coffee. A new coffee shop just opened up right across the street, so you decide to give it a try. The coffee is exactly what you were craving. It completely meets your needs. You've never had coffee that so perfectly met your coffee needs. It's fresh, it's aromatic, it doesn't have any yucky bitterness to it, it's everything coffee should be and nothing coffee shouldn't be. In fact, you never knew that coffee could be this good. So the next time you're craving coffee, you back to the same coffee shop again. And once again it meets your needs perfectly, so you keep going back again and again.

Now sometimes your tastes vary a bit, but it turns out this coffee can meet your needs even when your tastes vary. When you want something a bit richer, it meets your needs if you add cream instead of milk. If you don't want caffeine, the decaf is perfect. If it's hot out, the iced coffee is exactly what you're craving. Every time you go to the coffee shop to get something you're craving, their products fulfill your craving completely, and you've never found another coffee anywhere that fulfills your cravings nearly as well.

After this goes on for a while, it would simply no longer make sense to try new coffee shops, now would it? You wouldn't feel that it's dull or boring to keep going to the same coffee shop, because their coffee is so unbelievably good compared to any other coffee you've tasted or even smelled. In fact, you'd feel it's a privilege to have such perfect coffee right across the street, and you'd be thankful every day that they're right there.