Selfishness in relationships

It is a common view that the interests of two people involved in a relationship collide. To take a romantic relationship as the leading example: She likes Ballet, he likes baseball, nobody likes to do the dishes - therefore many times, one has to sacrifice and suffer while the other enjoys. The relationship, therefore, by this view, necessarily has internal battles, and selfishness is a threat to the relationship - something that pulls away from the "together" and builds a wall. 

The exact opposite is true, when "selfishness" is understood correctly. 

To explain what I mean, let's take the common notion of "selfishness" to its extreme: The ultimate selfish person would be the one who could make his girlfriend into a slave. She will cook for him, massage his feet, clean his apartment, and if needed, open beer bottles for him with her teeth. 
Most people will not dispute that this is the ultimate selfish person - concerned with nothing but his own “ass”. The other end of this idea of "selfishness" is the sucker - the woman from this example, who never gets what she wants and is always busy pleasing her man. 
One thing that’s obvious about this allegedly selfish person is that he acts to satisfy his immediate needs. But this is not the essence of selfishness.

To explain why, let's consider a whole different type of a relationship: a relationship where each one enjoys making the other person happy and cares about their partner's well being. 
In action, this means occasionally spending hard-earned money buying presents for the partner, giving them massage when they're tired, making food for them when the time and mood is right and giving them support and encouragement in their career.  

Are they "suckers" or "selfless" for doing such things for their partner? Similarly, is a mother taking care of her kids, paying for their college, instead of training them to be house slaves - a sucker, who is not concerned with her own well being? 

It is precisely their happiness and well being that the person from my example (and the mother) is motivated by, while the so called "egoist" I first discussed is not concerned with happiness at all - especially not in the context of the relationship. One cannot seek happiness in a relationship with someone one tries to enslave. And a person who prefers a beer over a happy relationship with his girlfriend (or boyfriend) is not concerned with his enjoyment. He does act to satisfy his immediate wants, but he does not seek the best possible for himself in life. 
The person who seeks the best for himself, tries to find ways to get out of a swamp – instead of occasionally scratching his bottoms when the swamp water irritate it. He does not adjust or accept the swampy in his life – he acts to change it.

Investing in those one loves gives tremendous value. It is ultimately one's “ass” that one looks after when investing effort in supporting a loved one. The smile on their face gives pleasure, their good mood is fun to be around and their psychological and physical well being is required to enjoy their company.

The other type, who cares best for his beer (to choose a random example) is looking, at best, for some sort of comfort from how much his life suck, but it is not enjoyment or happiness that he seeks in the relationship.  

To use an example to make this even clearer: If a person grows a plant, and spends time nurturing it – is he a selfless sucker, or is he acting selfishly? After all, he is working for the benefit of the plant. Wouldn’t he be selfish to say “the hell with it, I’m not going to enslave myself for the good of a plant”? 
It is easy to see that this thinking is ridiculous – a person nurturing a plant is doing it to enjoy it (for the fruit or the aesthetic value). The fact that it benefits the plant is irrelevant. 
Same thing is true if you replace the plant with a human being. 

Investing in your partner is ultimately investing in your own happiness. It is part of acting to make your life happy – and because of that it is selfish.  

Does this mean that meeting your partner's every requirement is always centered around one's well being? No. Investing in someone else as means to one's own enjoyment depends on one's mood, tasks for the day, personal interests, etc'.  

For example, if you are so bored with ballet, that if you go with your girlfriend to see it, even though her mood might be good afterwards, yours will be so low, you won't be able to enjoy her company at all - obviously in this situation it is not selfish to go see the ballet show with her. But, to give another example: if your time is free, you don't mind or like cooking, and your partner comes home exhausted and hungry - it increases your enjoyment to cook something for them and it is therefore selfish.  
About doing the dishes – assume two people living together, both equally busy, both finding the task annoying. Is it selfish to try to make the other person do it? Essentially, is it selfish to act unjustly to your partner to get away with doing dishes? 
It is not selfish for a few reasons: One is that you will be damaging your relationship – nobody likes to be treated like a slave – it is a certain romance killer. To prefer avoiding dishes over a happy relationship is not pursuing happiness, but the opposite. And the second reason is that being just to other people is a requirement of self-esteem (but I won’t get into it now). It is in both the partner’s interest to reach some just agreement to handle dishes in this case. Their interests do not collide when both of them have their best self-interest in mind. 

To further expand this understanding, consider the case of a battlefield: Is it selfish to stay in your hole, never sticking your neck out to shoot an enemy or help your fellow soldiers? No, it's stupid. Your fellow soldiers alive and well means more firepower. Cooperating with your fellow soldiers (such as providing backup) means you act in the most efficient way to defeat the enemy thus securing your own survival. The guy sitting in his hole doing nothing is escaping the reality of the situation - not acting to support his life. 
What will he do once all his other teammates are dead? His death will follow too. Cooperation with his team is required for his survival.

Does this mean you should do nothing but provide backup for your teammates? Obviously, this would be putting other people’s life above your own. The soldier in this situation has to primarily look out for his own well being, which in turn requires cooperation with the others, and helping them to the extent it serves one's cause (in this case, survival). 

In summary – the selfish person seeks happiness in life – and nurturing a person he loves is an extension of that. Selfishness is therefore a requirement for a good relationship – not a wedge. 
The interests of two such people in a relationship do not collide so long as they do not ignore reality. 
And the common view of selfishness is completely wrong – reversing the meaning of self-interest by presenting laziness and exploitation as selfish behavior, when in fact just cooperation with people is selfish.