Attachment patterns, fear of rejection, the anxiety that shows up in messaging.
No. Introversion is a temperament that involves a preference for less stimulation and smaller social settings, without distress. Social anxiety disorder involves fear of being evaluated, distress in social settings, and a desire for connection that the fear gets in the way of. Many introverts have rich social lives that suit their pace. Most adults with social anxiety would like to be more socially engaged than they are.
Texting strips out most of the non-verbal information people use to interpret a conversation: tone, expression, pacing, micro-pauses. The brain fills in the missing data, often with the worst-case interpretation. The asynchronicity adds another layer: the absence of an immediate reply is ambiguous, and the anxious mind is unusually bad at sitting with ambiguity. For close relationships, defaulting to a brief phone call usually resolves the anxiety faster than continuing the text exchange.
Anxious attachment is a pattern of relating in close relationships characterized by heightened sensitivity to signs of distance, a strong desire for closeness, and significant activation when contact slows. It is one of several attachment patterns described in the research; most adults show different patterns in different relationships and at different times. The pattern isn't a fixed identity. The activation can be worked with through awareness, gradual tolerance of distance, and treatment of the underlying anxiety.
Yes. Cognitive behavioral therapy with exposure has strong evidence as a standalone treatment for social anxiety disorder. Medication is added when symptoms are severe, when therapy alone has been insufficient, or when access to a qualified therapist is limited. For performance-only situations (public speaking, auditions), short-term beta-blockers are sometimes used.
The general principle: be specific about what is happening, not just that you're anxious. 'I get a hot wave in my chest before phone calls' is more useful than 'I have anxiety.' Name what helps and what doesn't help when the anxiety is active. Tell them what you would like them to do or not do in those moments. A short, specific conversation tends to land better than a long, abstract one.