It is a way to cope! Whether it's dangerous or not depends on how valuable the relationship is and to which degree it could become healthy, should the two involved parties start being self-aware, understanding their respective integrative attachment style patterns, and are willing to work on themselves!

Shutting down is a huge part of the Fearful-Avoidant strategies. Unlike coming from other styles, it may seem too harsh since it's in complete contradiction with their other side: very sweet, craving connection, and so agreeable.

That's why it's also called the "disorganized style". They're my favorite folks, and most unaware empaths and saviors belong to this group in my experience at least!