It isnt hard to understand the concept of loyalty in a networking environment when it comes time to refer business. Here are your circle of contacts. There are your clients. It is very easy to put both of them together. But other things constitute loyalty in a networking environment as well.
Loyalty means being present at networking functions- and participating.
Loyalty means never embarrassing another with your actions or words. Loyalty means being honest- even when its hard to do so. Loyalty means being a part of the solution not a part of the problem. People can sense when someone is looking out for the interests of the relationship as a whole or just looking out for their own interests. Business leads start to fall off when a person's loyalty is in question.