Tiers of Relationships

My observations have led me to develop a way of examining how people matter to each other.
I have organized this into tiers.

Over time I have defined and redefined the tiers and reordered their numbering system.

Here is the current version, based on my many years of watching human behavior and experiencing it for both sides of a human friendship.

Tier 6 - Both you and the other party have near continuous thoughts of each other and have an active desire to keep each other thoroughly entrenched in each-other's life. The other person is a top priority in each of your lives and schedules are altered to make time for one-another as needed. This relationship, when a friendship, spans distances through active use of modern technology.
Tier 5 - You and the other person both actively engage with each other and enjoy each-other's company but failure to align schedules is acceptable. Physical distance can cause this relationship to slowly degrade.
Tier 4 - You enjoy this person's company and expect to see them at events and gatherings. You never invite them because you assume that they already know or that someone else has already invited them. You don't tend to notice if they are missing from an activity and assume they are popular enough to be at some other activity instead.
Tier 3 - If this person talks to you or is engaged in a conversation you find interesting you will enter into a conversation and enjoy it. You don't generally start conversations with this person. You never actively invite them and they don't invite you. It is possible you do not even know the other party's name.
Tier 2 - You recognize this person and will convey general greetings and small-talk as needed.
Tier 1 - You recognize this person but do not generally acknowledge them in any way.
Tier 0 - Neutral - you have never seen or met this person before
Tier -1 - See Tier 1, but in a repellant direction instead of an attractive one.
Tier -2 - See Tier 2, but in a repellant direction instead of an attractive one.
Tier -3 - See Tier 3, but in a repellant direction instead of an attractive one.
Tier -4 - See Tier 4, but in a repellant direction instead of an attractive one.
Tier -5 - See Tier 5, but in a repellant direction instead of an attractive one.
Tier -6 - See Tier 6, but in a repellant direction instead of an attractive one.

There may be professional research that defines these, or a similar, relationship structure. I have done no active research on the subject, only observation and classification.