Theories & Development of Interpersonal relationship ?

Theories
Psychologists have suggested that all humans have a basic, motivational drive to form and maintain caring interpersonal relationships. According to this view, people need both stable relationships and satisfying interactions with the people in those relationships. If either of these two ingredients is missing, people will begin to feel anxious, lonely, depressed, and unhappy.[3]
According to attachment theory, relationships can be viewed in terms of attachment styles that develop during early childhood. These patterns are believed to influence interactions throughout adulthood by shaping the roles people adopt in relationships. For example, one partner may be securely attached while the other is anxious and avoidant. Thus, early childhood experience (primarily with parents) is believed to have long lasting effects on all future relationships.
Social exchange theory interprets relationships in terms of exchanged benefits. It predicts that people regard relationships in terms of rewards obtained from the relationship, as well as potential rewards from alternate relationships.[4] Equity theory stems from a criticism of social exchange theory and suggests that people care about more than just maximizing rewards. They also want fairness and equity in their relationships.
Relational dialectics regards relationships not as static entities, but as continuing processes, forever changing. This approach sees constant tension in the negotiation of three main issues: autonomy vs. connection, novelty vs. predictability, and openness vs. closedness.

[edit] Development
Interpersonal relationships are dynamic systems that change continuously during their existence. Like living organisms, relationships have a beginning, a lifespan, and an end. They tend to grow and improve gradually, as people get to know each other and become closer emotionally, or they gradually deteriorate as people drift apart and form new relationships with others. One of the most influential models of relationship development was proposed by psychologist, George Levinger.[5] This model was formulated to describe heterosexual, adult romantic relationships, but it has been applied to other kinds of interpersonal relations as well. According to the model, the natural development of a relationship follows five stages:
Acquaintance - Becoming acquainted depends on previous relationships, physical proximity, first impressions, and a variety of other factors. If two people begin to like each other, continued interactions may lead to the next stage, but acquainance can continue indefinitely.
Buildup - During this stage, people begin to trust and care about each other. The need for compatibility and such filtering agents as common background and goals will influence whether or not interaction continues.
Continuation - This stage follows a mutual commitment to a long term friendship, romantic relationship, or marriage. It is generally a long, relative stable period. Nevertheless, continued growth and development will occur during this time. Mutual trust is important for sustaining the relationship.
Deterioration - Not all relationships deteriorate, but those that do tend to show signs of trouble. Boredom, resentment, and dissatisfaction may occur, and individuals may communicate less and avoid self-disclosure. Loss of trust and betrayals may take place as the downward spiral continues.
Termination - The final stage marks the end of the relationship, either by death in the case of a healthy relationship, or by separation.
Friendships may involve some degree of transitivity. In other words, a person may become a friend of an existing friend's friend. However, if two people have a sexual relationship with the same person, they may become competitors rather than friends. Accordingly, sexual behavior with the sexual partner of a friend may damage the friendship (see love triangle). Sexual relations between two friends tend to alter that relationship, either by "taking it to the next level" or by severing it. Sexual partners may also be classified as friends and the sexual relationship may either enhance or depreciate the friendship.
Legal sanction reinforces and regularizes marriages and civil unions as perceived "respectable" building-blocks of society. In the United States of America, for example, the de-criminalization of homosexual sexual relations in the Supreme Court decision, Lawrence v. Texas (2003) facilitated the mainstreaming of gay long-term relationships, and broached the possibility of the legalization of same-sex marriages in that country.