Virgo appreciates social interaction, but finds it taxing. They obviously value their alone time.
Virgos like being engrossed in research or writing and are always seeking to better themselves.
Pisceans appreciate being with others, yet they also prefer solitude. People spend much time alone in their heads.
Pisces is a highly imaginative sign that spends a great deal of time crafting alone.
If Pisces is required to dress up and go out for a social engagement, they would rather stay in bed and rest.
Caps can be extroverted at times and entirely content to be alone and mind their own business with others.
At times, a Caps may want to isolate oneself and have limited social contact.
It's entirely possible that they're just too busy to go to social events, or that their current emotional state requires them to be alone for a while.