Probation in Relationships?

When starting a new job, new employees are expected to pass a probationary period. At the end of that probationary period an evaluation is conducted. This evaluation is an appraisal of whether or not the employee accomplished the goals set forth by the company using the skill sets they presented during the interviewing process, At the end of the evaluation, it is determined that there are 3 outcome options. First is an extension of probation. This is due to the employee needing more time to show the company that they are committed to being a great asset to said company. Second is passing probation. Now the employee has shown the company they are serious about potential expansion and becoming mutually successful. The third option is the employee being fired. This occurs because the employee has not proven themselves worthy or able to succeed with the company. This is based on their actions including the interviewing process. The employee’s lack of commitment to the company, not meeting deadlines on time, even going as far as being disrespectful towards the company. I say all of this to ask one question. Why don’t we adopt this practice when it comes to our relationships?