> The alternative is being a fortress - with all the relationship problems that entails.

I’m reminded of the concept of siege mentality.

https://en.wikipedia.org/wiki/Siege_mentality

> In sociology, siege mentality is a shared feeling of victimization and defensiveness—a term derived from the actual experience of military defences of real sieges. It is a collective state of mind in which a group of people believe themselves constantly attacked, oppressed, or isolated in the face of the negative intentions of the rest of the world. Although a group phenomenon, the term describes both the emotions and thoughts of the group as a whole, and as individuals. The result is a state of being overly fearful of surrounding peoples, and an intractably defensive attitude.

> Among the consequences of a siege mentality are black and white thinking, social conformity, and lack of trust, but also a preparedness for the worst and a strong sense of social cohesion.