If there was ever an ideal kind of relationship, I would reckon it is one that thrives on ideas (and wants), not needs, with both parties in it of enough egotism and self-esteem to be self-interested but not selfish, and spared from the chains of emotional dependence.
In psychology, there are two types of relationships that work - the secure-secure relationship and the anxious/ambivalent-avoidant relationship. For the uninitiated, secure people are those who are trusting, socially comfortable and form typically healthy relationships with people, be they friends, significant others or kin. Anxious/ambivalent and avoidant people are people who have trusting issues. Anxious/ambivalent people manifest it by being neurotic, clingy and possessive because they are afraid to lose those they finally dare to allow into their lives. Avoidant people manifest the difficulty to trust by being anti-social, reclusive and introverted, keeping to themselves most of the time.
Anxious/ambivalent-avoidant relationships often comprise of the female taking on the emotional possessive role and the male taking on the avoidant, silent role, and it works because these are socially accepted gender roles. It also works because both parties are a good fit when they can provide what each other needs. The anxious/ambivalent person thrives on the uncertainty and ambiguity of the avoidant person's reclusiveness, while the avoidant person thrives on the possessiveness and persistence of the anxious/ambivalent partner.
When a relationship sustains itself through needs more than desires, I would doubt its synergy. It is like Maslow's hierarchy of needs - if you're still grappling with the basal necessities of food and water, you will never get to the higher levels of satisfaction.
That's where a healthy dose of self-esteem and egotism comes in. It is unfair to say that everyone should be like secure people, because secure people don't happen overnight, and people are who they are because of their life experiences. But the reality of the situation is that secure people, with their healthy doses of self-esteem, have enough pride in them for them to believe that they deserve a certain level of return when they invest in a relationship.
What then happens in a secure-secure relationship, where both parties behave in this seemingly economic, self interested way, is that they know what they're worth. At this point, there may be those who say that this just seems heartless, results in people being non-committal and leaves room for people to dump their loved ones in the presence of better alternatives. But instead of looking at it so negatively (which also only happens because people who criticize this are probably anxious, neurotic and afraid of loss), the result is that both parties actually know their value because they have made it into each other's lives, and this is strongly reaffirming of each person's self worth. I made it into your life, and you made it into mine, and this is the strongest endorsement of your quality to me and my quality to yours.
Once needs can be put aside because they are thus fulfilled, there is so much else to look forward to and achieve together. When you don't spend half or more of your time worrying about losing someone, you're trading your emotional chains for freedom. That is why egotism works, and is good. If you know what you're worth, there's always a safety catch that stops you from being too suckered into liking somebody. If he or she falls short of your expectations, can't make up their mind or does other silly things, then your pride will tell you that you're just wasting your time and you deserve better than settling down with this.
The desire to trade up always happens whether you're a secure person or not. But by the time people in anxious/ambivalent-avoidant relationships realize they feel too jaded and yet too comfortable where they are, it gets harder to understand the reality of their predicament. So if one person starts to feel shortchanged by his/her situation, the result is often a fling with someone else, in order to trade up (even just for a moment) and to satisfy unfulfilled desires that echo in hearts that have lost their fires.
In the end, it's the synergy that becomes the indicator. At the heart of it all, are you looking forward to meeting your loved one to create and discuss ideas, or are you just looking forward to meeting your loved one because you're afraid he/she might leave you?
Whether self-esteem breeds the ability to believe that one always has options (so that one is never at the losing end), or one's options gives him/her confidence and hence self-esteem, a little bit of self belief and egotism always goes a long way. At the end of it all, always remember what you're worth and don't sell yourself short. What can you offer to the person you're gonna chain up anyway, if you're not completely happy?