There is actually a company ecology model (Moore, 2006) that varies from company to company, and analyzes the data obtained from customer surveys, sales vs. purchases, and social influencing. From these research models (although there could be several others) these types of relationships between companies and customers have been identified:
Intentional relationship- occurs when a customer uses a specific company over time because of contract negotiation agreements due to quality, price, or availability of resources.
Behavioral relationship- the customer chooses his or her "go-to" company because it is the customer's favorite. This is indicative of a trust factor that has been created between the company and the client.
Dedication relationship- the customer chooses the company because of its name, logo, social influence, or because of the company's association to something that is meaningful to the customer. For example, a young man may switch tea brands, let's say, from Tetley's to Typhoo because Typhoo sponsors his favorite Rugby team. Or, one may prefer to drink Pepsi over Coke (despite of personal taste) simply because Pepsi may be sponsoring animal rights groups that the customer also supports.
Constraint relationships- these are not necessarily positive relationships, because the connection may not be made by the customer's personal choice. This type of relationship occurs when the customer's lack of options leads to the selection of a company that just so "happens to be there". The best thing for a company to do is to increase its levels of quality control and customer service to "gain" the trust of the client and keep the customer fixed.
Research and influence groups divide customer relationships on many more sub-strands of client/company connection, but these four are perhaps the most influential in market terms.