2. Being "there" for for each other...
in a balanced healthy way
Interdependence is a learned thing, because most of us weren't raised in a healthy empowered interdependent way. Interdependency from codependency is the transition that heals relationships. Tough love doesn't work.  It's cruel and gives the person a feeling of being abandoned in their hour of need. Healthy support is vital to someone in need of healing.
We come together in relationships to heal... we come to grow past who
we've been programmed to act out... to come closer to who we truly are.
Codependency is helping someone to the point of hurting yourself, but doing it anyway because there's no way to negotiate or re-negotiate with honest communication, for what ever reason.
Interdependency is being able to help when you can, comfortably... and negotiate or re-negotiate by communicating honestly & lovingly about how their behaviors make us feel,
in a way & time so they will be best heard & understood.
Each person taking care of their own needs as much as possible,
so that the shared time is sacred.
A relationship is the space between the two (or more) people & needs to be protected by both
(or the group of) people involved in it.  Next time a disagreement comes up try this:
See the relationship as the third person and each one can talk to it and apologize to it for the hurting each have done, that may have damage the relationships trust.
Do this from an objective point of view, with no blame involved... in the name of growth.
(Kids become the physical form of this truth.)