The former world number one blamed an "extremely stressful" time in her personal life for the withdrawal, calling her decision to play a "mistake" and pledging to learn from the incident.
Azarenka was trailing 6-2 3-0 against 16-year-old Czech Fruhvirtova when she abruptly ended the match, having earlier shouted "why am I here?" at her coaching team.
The two-time Australian Open champion also broke down in tears after her third-round defeat to Elena Rybakina at Indian Wells earlier this month, deleting her social media accounts in the aftermath.
Via a statement released after her retirement from the tournament, the Belarusian said she should not have gone onto the court to face Fruhvirtova, blaming an "extremely stressful" time in her personal life for the incident.
"I shouldn't have gone on the court today," the 32-year-old said.
"The last few weeks have been extremely stressful in my personal life.
"[My] last match took so much out of me, but I wanted to play in front of a great audience as they helped me pull through my first match.
"I wanted to go out there and try but it was a mistake. I always look forward to the challenge and pressure of competition but today it was too much.
"I have to and will learn from this."
As a Belarusian, Azarenka has had to compete as a neutral player since her country's regime helped enable the Russian invasion of Ukraine, with the participation of sportspeople from the two countries being a subject of intense discussion.