Foundations...

Precedent, as defined by Merrian-Webster....

²prec·e·dent

noun \ˈpre-sə-dənt\

: a similar action or event that happened at an earlier time
: something done or said that can be used as an example or rule to be followed in the future

: the usual or traditional way of doing something

Full Definition of PRECEDENT

1

:  an earlier occurrence of something similar

2

a :  something done or said that may serve as an example or rule to authorize or justify a subsequent act of the same or an analogous kind precedent

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b :  the convention established by such a precedent or by long practice

3

:  a person or thing that serves as a model 

 

In this context, we use it as a noun. Even further, we use it as a way to describe why an action taken at a previous juncture was used to serve as an example to be used in the future. In this way, we see that anything that has been set as a precedent in a relationship, be it business, personal, or romantic, can be used to steer clear of, or to expect another action taken in a similar manner. 

Without being too cryptic, take this situation as an example: person asks other person to be at a job interview @ 9am. Interviewee can't make it to said interview because of another emergency or commitment, but yet made the commitment to the interviewer to be on time. Interviewer decides that although interviewee is fully qualified, this could be SETTING A PRECEDENT and decides to not reschedule. Interviewee then feels a sense of betrayal because they feel that this was something out of their control. Unfortunately, the interviewee does not see the forest for the trees, because this PRECEDENT has been set a while ago due to some choice or a path chosen incorrectly. 

Now in the matter of our lives, the foundation we set with people, businesses or partners all hinge on the precedents we set with them. This is how history works; the adage is "if we do not take history in to consideration, we are doomed to repeat it".