There are many aspects that can be taken into account when observing a relationship, such as feelings, interactions, common interests and needs, conflict resolutions, expectations and goals, etc. I will give you an example of a tree notation to observe a relationship using 3 levels of nodes:

• Relationship
  • Feelings
    • Awareness of feelings
      • Expression of feelings
      • Managing feelings
  • Interactions
    • Awareness of interactions
      • Improved interactions
      • Effective communication
  • Common interests and needs
    • Awareness of interests and needs
      • Exploration of interests and needs
      • Alignment of interests and needs

This example to observe and describe is given as a guide. It may vary according to context and specific needs. It's important to note that this structure can be adapted or supplemented with other nodes for additional information according to your needs.