A big part of the science of international relations is the study of the causes of war. But it’s also about how nations can cooperate — like signing treaties, providing aid and generally promising not to kill each others’ citizens. It considers humans on the grandest, most violent scale — asking how we can overcome what might be a fundamentally selfish, fearful human nature to not just coexist but do better than we could alone.

But over 15 years of studying, researching and teaching international relations, I’ve learned that it’s also a deeply personal science, involving commitment, communication and trust. Those things can help reduce conflict and increase cooperation between nations … and people (in my experience, at least). So, seeing how it’s Valentine’s Day, I bring you eight pieces of relationship advice courtesy of international relations.

1. Say what you mean, and prove it

We’ve all heard the adage that you should pay attention to what someone does, not what they say. International relations scholars agree. Countries that send “costly signals” — taking an action that incurs some cost, such as moving troops away from a border or disabling a nuclear program — are better able to communicate their intentions in a convincing way to other countries.

You can see some of that idea at work on Valentine’s Day: Buying roses makes that “I love you” more credible, said James Morrow, a professor of political science at the University of Michigan and co-author of “The Logic of Political Survival.” “An engagement ring is also a costly signal,” he added.

You can apply this idea to other areas of your relationship too. If you want your partner to believe that you’ll finally make time for a vacation, for example, book the tickets.

2. Have an audience

Proposing at a baseball game may seem cheesy and cliché, but there may be something to it. Leaders who generate “audience costs” — that is, they make public promises — tend to keep those promises more often than leaders who keep their intentions to themselves or confined to a small circle. The idea here is simple: accountability. The trick is you need an audience whose opinions matter to you. That’s, in part, why democratic leaders are often better at keeping promises than authoritarian ones — the former are more accountable to their public.

Likewise, you might consider proposing in front of your parents or a group of friends rather than a bunch of drunk strangers watching a ball game.

3. Reciprocity is king

Many scholars considered sustaining international cooperation without a central world government nearly impossible until they discovered the power of the simple rule of “tit-for-tat”: If another country does something nice for you, do something nice in return. They will then return the favor, then you will, and so on — until you’re both living happily ever after.

So, if your partner takes out the trash this week, do it the following week, and you’ll never have to discuss it again. Domestic bliss is yours! “You can also think about tit-for-tat as implicit punishment,” said James Fearon, a professor of political science at Stanford University, “If you don’t take out the trash, I’ll stop walking the dog….”

4. But so is forgiveness

OK, your partner didn’t take out the trash last week. You’re entitled to not take it out this week. But then, forgive and start over. Research shows that punishing someone repeatedly for one wrongdoing — similar to a strategy called “grim trigger” — is less effective at sustaining long-term cooperation than just punishing a nation once and moving on.

5. No disagreement is an island

Your partner wants to use your first vacation in forever to go to the beach. But you want to go to the mountains. Stalemate! Well, maybe not. There are lots of creative ways to solve an impasse like this, including “issue linkage” — for example, where a person’s advantage in one domain can be countered by providing a benefit to the other person in a different domain, making what would be an otherwise lousy outcome much better. Let’s say Country A wants Country B to remove steel tariffs. Country B could agree, but only on the condition that Country A curbs its greenhouse gas emissions. So, go ahead and give in on the beach — but then you’re entitled to not do the dishes for a week.

6. Careful, conflict is easily escalated

One of the most enduring puzzles about war is that it breaks out even though both parties would be better off coming to a peaceful, negotiated settlement. The same thing can happen in relationships, where after a huge fight you wonder what it was you were fighting about in the first place.

One reason escalation is so easy in both scenarios is that there’s a temptation for each side to bluff about how far they’re willing to go to get the other side to back down. This is because each side has an incentive to act like they care more about getting their preferred outcome than the other side so that when the time comes to draw up an agreement, they get the better deal. The problem is, when both sides (rationally) pretend to care more than they do, they may find themselves in a position where they’ve escalated and can’t back down (thanks to the aforementioned audience costs, for example). In technical terms, this means they’ve shrunk the bargaining range. Trump shouldn’t threaten North Korea with a nuclear attack unless he’s prepared to do it; likewise, don’t threaten to move out unless you really think that’s the solution.

7. The right third party can help

Third parties intervening in a dispute between two countries can help them keep peace, especially when the arbiter is seen as legitimate by both sides. Get a good therapist, and get everyone’s buy-in.

8. Even symbolic stuff can make a difference

Some research suggests that signing an international agreement, like the Paris Climate Accord, can compel countries to change their behavior, but other research shows agreements only attract countries that are already following the rules. Marriage may operate the same way — it could change your behavior, but it’s more likely only going to reflect the relationship as it is. Still, neither are necessarily useless — agreements of all kinds can serve as “focal points” that clarify what kind of behavior the other is going to follow.

So there you have it! All of these are easier said than done, of course. We still see countries go to war and we still see couples fight. But these are the strategies people use to cope with “uncertainty about the future and the intentions of others,” Alexander Von Hagen-Jamar, a postdoctoral fellow at Lund University, said.

“Leaders of countries and people in relationships are both constantly wary of having their territories attacked or their hearts broken,” said Sarah Croco, a professor of political science at the University of Maryland.

Yet, it all may be worth the risk of conflict if it helps us get to cooperation, because cooperation is more than just the absence of war. It means being able to accomplish things we can’t alone — like operate an International Space Station or, you know, fall in love.