"Line of Best Fit"

Though it is most commonly used describing a algebraic expression, the line of best fit refers to the approach of modeling the relationship between two or more variables for purposes of predicting values that may not be displayed on the plot. The straight line connecting the two variables is called the "line of best fit."
My interpretation of this expression applies to any relationship between two or more people(variables) in any situation whether it may be with a friend, co-worker, relative or significant other. The line of best fit represents the most comfortable connection between the two(or more) people and is used to determine the values that both parties share comfortably. Say you're holding on to a relationship solely built on what little you both have in common. The best way to determine whether or not the two variables will co-exist happily relies on the amount of good compared to the amount of bad.