Relationships have normal ebbs and flows. They do not automatically get better and better where the participants learn more and more about each other. At times the relationships is very open and sharing. Other time, one or both parties to the relationship need their space, or have other concerns, and the relationship is less open. The theory posits that these cycles occur throughout the life of the relationship as the persons try to balance their needs for privacy and open relationship.
Persons allow other people to penetrate their public self when they disclose personal information.
The decision to disclose is based on the preceived rewards the person will gain if he or she discloses information. If a person perceives that the cost of disclosing information is greater than the rewards for disclosing information then no information will be disclosed. The larger the reward - cost ratio the more disclosure takes place. If you think to the relationships you have been in you will probably find that in almost all of them more disclosure took place at the outset of the relationship than at any other place. That happens because people initially disclose superficial information that costs very little if another person finds it out.