Though they seem to arrive "out of the blue", these intense anxiety experiences tend to be caused by a specific trigger like experiencing an anxiety-provoking situation:

The answer is "Panic Attacks".

A panic attack is the unexpected beginning of extreme dread or inconvenience that achieves a top inside minutes. Panic attacks can happen out of the blue amid a quiet state or in an on edge state. Despite the fact that panic attacks are a characterizing or defining panic issue, it isn't exceptional for people to encounter panic attacks with regards to other mental issue.

intimacy, passion and commitment are the components of a interpersonal relationship emphasized in the triangular theory of love by robert sternberg.

the triangular theory of love says love can be comprehend as this componest form the vertices of a triangle.  

intimacy relates to feelings such as of closeness and connection;

passion relates the drives that brings people together, as physical attraction.

commitment relates to the being in a long-term relationship.