The Prisoner's Dilemma

Recently, I came across something that I see played out often in human relationships. 

Its called the 'Prisoner's Dilemma'. 

Basically, lets say two people have been arrested for theft and placed in separate cells so that they can't communicate. The following offer is made to each. “You may choose to confess or remain silent. If you confess and your accomplice remains silent you go free & your partner gets punished. Likewise, if your partner confesses while you remain silent, they go free while you get punished. 

If you both confess, you both will get punished, but a little less. 

If you both stay silent, I will let you both out with a fine, but no prison.”

The “dilemma” faced by the prisoners here is that, regardless of what the other will do, each is potentially better off individually, by confessing than remaining silent. (Take a moment and play out the cases if you like). On the other hand, if both confess, they both end worse off. 

The possibilities of substitutions are many.. For example, try replacing 

"robbing a bank" with "had a fight",
"communicate" with "read the other's mind",
"stay silent" with "admit mistake",
"confess" with "refuse to yield", 

and "go free" with "take advantage", you'll see what I mean.. 

You can even entertain & convince yourself by choosing cases like business partnerships, romantic situations, etc. 

The scenario becomes interesting when played multiple times in succession between the same 2 people. 

E.g. two people have successive fights. Maybe, after the first fight, A would admit his mistake. Now, B's reaction will determine what A does after the second fight. And so on. Its clear that if at any point either of them puts self above the other, they may benefit in that one iteration, but BOTH lose in the long run.

Then, we get to the most interesting case, where
A experiences the first iteration with B, (say, A loves B) then B cheats A
A experiences the second iteration with C,  (say, A manages to fall in love again, with C) then C cheats A too

A doesn't learn from the past and enacts the third iteration with D, (i.e. falls in love once more, this time with D) .. 

In this case, lets assume for a moment, that D is playing fair. I.e. D is not going to cheat A, and D reciprocates A's honesty. Given the past, A will almost certainly penalize D, either by being suspicious about D's intentions, or not really putting 100% into the relationship, or by just forcing himself/herself OUT of, or AWAY from the relationship as a self-defence mechanism.
D, now, in turn would go about penalizing potentially harmless people because of A.. Lets pause and think of alternatives.

There are many suggested solutions to maximize the group benefit. (You can read more, http://www.google.co.in/search?sourceid=chrome&ie=UTF-8&q=prisoner's+dilemma)

But in the context of human relationships, I see one overlooked possibility.. 

IF the two people in any iteration trust each other completely AND each cares more about the other person than themselves, there's no dilemma. 

Even in the most interesting (multi-person) case, if A can take a leap of faith after knowing D is trustworthy, A & D would both benefit.