Boundary doors are the most mature boundary anatomy to have. They operate with one's decisional capacity to use wisdom, a combination of conscience, or ethics, and intuition, or a read on the level of opportunity in the environment.

As such, they are the highest character maturity of the boundary anatomy available to us. They are the least narcissistic, as compared to Boundary Holes and Boundary Walls, and can be envisioned as a "door" that may open to others and their communication and partnership (Intimacy), like saying YES to others, on certain conditions. But they may also close to the communication and partnership with others (Independence), like saying NO to others, conditionally. As a result, the Boundary Doors make us DYNAMIC, in that we can relate differently to the same people depending on his they treat us, and what kinds of deals they offer us.

We can then take in and accept communication, resources, and emotion that is good for us, while blocking that which is bad for us, even with the very same person we are relating to.  This is far more mature, adaptive, and fit to the real world of adults, where people can change and alter their approach to us depending on the limits we set and preferences we have.

This makes for a partner who is interdependent, rather than either codependent or overly independent.

In addition, Boundary Doors equip us for mature social interactions, and mature romantic partnerships because they are almost always one of the working parts of our more Mature Ego Defenses, or Defense Mechanisms - such social habits as humor, altruism, anticipation of the future, and suppression of problems that we can't solve at the moment.