“Opposites attract” goes the saying, but for that attraction to translate into a successful long-term relationship, the word “opposite” must refer to a complementarity of skills rather than to very different preferences. In short, you need to be compatible if you want your relationship to last.

Most of us think of compatibility as liking the same things, but it is actually much more than that. For a relationship to prosper, it needs to fulfill four basic requirements for both partners. They are, by order of importance:

1. Trust:

For a couple living together, compatibility of values is an essential success factor: Each of us has values and principles that can be different. An innocent white lie could be acceptable to you but a major problem to your partner; cheating a little on an exam not a big deal for one but a major issue for the other; throwing away excess food normal might be for your neighbor but appalling for you. These are relatively small issues and there are many bigger issues a couple will encounter, such as religious tolerance, sexual behavior, children’s education, etc. For a couple to be able to trust each other, values must be in harmony: They don’t need to be irreproachable, just in agreement about what is OK and what is not. Bonnie and Clyde are a good example of a couple whose values we would probably disagree with, but who have developed their own code of ethics. Your partner’s values don’t need to be exactly the same as yours, but if you understand them, can predict them and can tolerate them, you’re compatible.

2. Assimilate:

Your partner is someone you will spend a lot of time with and lose a lot of privacy to. We have a tendency as humans to reject any foreign element trying to become part of our world: Ask any doctor who knows about organ transplants. Just as an organ that should not be rejected, any successful partner needs to be assimilated. That is where three types of compatibility are important:

Emotional compatibility: You are emotionally compatible when you are comfortable with each other’s reactions and emotions: an outburst that some people find funny, cute or endearing can be rude, irritating or obnoxious to others. A person you find too negative and dramatic is in someone else’s words sensitive and full of life. Alternatively, a person you see as positive and uplifting is for someone else unrealistic and out of touch with feelings and reality. You don’t have to be similar, but you need to be comfortable with each other.

Aspirational compatibility: You are aspirationally compatible when you are comfortable with each other’s higher calling in life: given that your partner is going to spend a lot of time with you, your ambitions can’t be totally different: he/she can’t be focused on climbing Mount Everest while your idea of self-realization is having tried all the clubs in Miami, Vegas and LA. Here you don’t need to have the same aspirations, just have objectives that do not conflict with one another.

Risk-taking compatibility: Living together means sharing a present and a future. When one partner is ready to gamble it all for the sake of improvement while the other values stability against anything else, you have a problem. When you always go to the airport 3 hours in advance and your partner always has to wait till the last minute, it can get tiresome. Two people can’t be very far from each other on this metric and expect a long and happy relationship.

3. Boost:

You are not together just to share resources, you should also be positive for each other and boost each other. For that to happen, three types of compatibility come into play:

Skills complementarity: This is where the “opposites attract” saying rings true. Getting a different perspective enriches your life and your relationship. Or getting help in an area you do not master. Going into a new venture knowing that your partner has your back. Knowing that life without your partner would be more difficult. A relationship is balanced when each side can contribute to it.

Compatibility of initiative: Is one of you always the one making the first step about activities, sacrifices, making time for special occasions? Is it always the same person that has to make the first conciliatory move when you have a fight? Alternatively, does one partner feel crowded by the ever enterprising other? If so, there is an imbalance that could drain the relationship.
Cultural compatibility: Our culture comes from our community, religious beliefs, education, language, cuisine, etc. The more diverse the couple is, the richer its interactions and achievements. However, with diversity also comes the risk of intolerance and one partner consciously or unconsciously trying to diminish the other. Here, the true test is the couple’s evolution over time: are the cultural differences increasing or decreasing? As the couple develops its own culture, they should be decreasing; the opposite is an early indicator of danger.

4. Enjoy:

You can be great together in terms of trust, acceptance and achievement but ideally you still have to enjoy each other to cement your long-term success. This part is what most people have in mind when the word “compatibility” is mentioned:

Physical compatibility: Do you find each other attractive? Is your sexual chemistry satisfying? Do you enjoy sharing the same bed, looking into each other’s eyes, touching, embracing?

Transactional compatibility: Do you like the same movies? Do you share the same hobbies, the same books, the same conversations, the same food? Again, you don’t have to be totally similar; you just need to have enough interests in common to enjoy being together at least as much as being apart.

Compatibility is important, and so is being generous. The last thing I would want you to do is to use this article to judge or blame your partner. It is meant to help you understand your relationship and whether and how you can work on yourself to improve it.