Awareness and air
There is not much to write home about these features. Both are present as observer, though not visible. Both are very important from the point of view of the transformation that takes place in their presence. In human relationship this awareness is what can continuously guide you in the proper direction. The idea behind this simile is proper analysis of conjugal relationship vis-a-vis sex. This is very important especially in our times.
We all know how strong concrete is and that the strength is all about combining the right thing in right proportion in the right place at the right time. The synergistic effect that it creates is unbelievable.
Now let us move to conjugal relationship. There is no doubt that each of the seven faculties are important and distinct in their own way. Each have a well defined role too. Now fruitful relationship is all about knowing and combining these faculties in the right place in the right proportion at the right time.
Awareness means detached observation. One should know what one is doing. Meditation will help improve the awareness. Detached observation will help see things in proper light. Awareness also enables you to have a second look at things and correct if necessary.
If something goes wrong with a relationship, by cross checking you can find whether some faculties remained silent or out of proportion or out of order and proper remedial measures can be taken.