So, if you ask someone out and they say, “I’d love to, but I have to study tonight,” what they are really saying is that the benefit of going out with you is less than the cost — the study time they would give up by going out with you.
In short, just because you’ve been dating someone for a long time, that doesn’t mean you should stay together forever.
Eventually, the marginal benefit becomes less the than marginal cost.
Now, the real benefits and costs that people make decisions based on are what economists call “marginal” benefits and costs. And this concept can help us understand why people date each other at all. But to narrow it down, let’s assume that you’re at a stage in life where you are ready to find a spouse. Let’s use of each month of dating is that it brings more information to you about your partner; each extra month also has a marginal cost such as time not spent with another person or simply being single.
The optimal amount of time to date is until the marginal benefit (MB) of continuing to date is equal to the marginal cost (MC) — what one gives up.
(Whether it takes months or years until MB = MC is subjective.) When MB = MC, it may be time to consider tying the knot.
If one partner decides to propose, no matter how romantic the setting and their words may be, what they are really saying behind those tears and poetic lines is, “The marginal benefit of dating you is now equal to the marginal cost.But how about we meet for lunch on Tuesday instead?” Through her responses, Jill is sending a clear signal to Jack.Stereotypically, our weekend nights (i.e., Friday and Saturday) are the “prime” nights either to go out with a significant other (or someone we hope will become a significant other) or to party with our friends. Jack might say to Jill, “Hey, would you like to go out to dinner this Friday night and then go to a Sharks game?” Jill might respond with, “I’d love to, but I have to study this Friday night. ” Or Jack might say, “Jill, I’d like to take you out to a play this Saturday night up in San Francisco and then we can go to this really popular restaurant afterward,” and Jill might reply, “Jack, I’d love to, but I have to wake up really early on Sunday morning to run some errands.What Jill is really saying is, “You want me to give up 4–6 hours of my precious Friday night sitting in a restaurant and then watching a hockey game with you? Let’s do coffee instead because I really don’t have much to do on Monday anyway and having a cup of coffee might take at most an hour, and I guess you’re nice enough to look at.” Out of politeness, most people don’t say that, but economics says that the opportunity cost of a Friday or Saturday night date is too high to go out with someone we feel lukewarm about.