I think ultimately, what we are obsessing with and constantly struggling against is not "your" need/interest versus "my" need/interest, but instead my own or your own short term need/interest and long term need/interest.

I would like to illustrate this by starting with explaining why the needs of us are essentially not conflicting.

One of the basic assumption is people are self-interested, and we all value our happiness over theirs. Prisoners' Dilemma models were decided to find out what is the best strategy in each different setting. In a long term repeating game, the overwhelming winner is "tic for tac", meaning I will repeat whatever strategy you applied in the previous game, and this will eventually leads to all cooperation solutions.

One example is the open source software, which actually help the creator nice profits. Another example is improving of management strategies for corporations.

So, what's the source of conflicts? Most of the time, it can be traced to the conflicting interest for the same person - desire for different things, or the short term v. long term.

I always tell people the opportunity cost for studying is too high b/c I can otherwise be having fun or working to make money. However, the long term paid off of having better education and more skills is plausible. In order to be making more money ten years from now, I choose to sacrifice some joy or potential income today.

It does not mean we are making irrational decision by having fun now because there are two critical factors influencing our decision making: marginal rate of substitute and discounting rate for future income/utility. Discounting rate of future utility is obvious, and the marginal utility of substitute is between the joy of say watching a movie now and the feeling of satisfaction from knowing I am working hard for tomorrow's exam and will do good at it and potentially (with a certain range of probability of) getting a better job in the future.

Nevertheless, the origins of conflicts are from different marginal rate of substitute and discounting rate for future income/utility varying from person to person.

The model is: future income * probability to gain that income * discounting rate
= current utility of expectation future utility
when: enjoy life now / current utility of expected future utility
= marginal rate of substitution,
we are in an indecisive mood, otherwise, we will decide to do one or the other.

Despite of all these differences, we all hang out with people having similar marginal rate of substitute and discounting rate as we do. Just for different things. We go movie with friends who have higher marginal rate of substitute of movie over other things; we go drinking with people who have as low of discounting rate of not having a headache tomorrow morning as we do.

Then, each individual has a very complex set of marginal rate of substitute and discounting rate, which are dynamic, and we don't always make the same decisions. At the end of the day, we are just conflicting with ourselves, internally, indecisively and infinitely.