Azarenka has since got Wim Fissette as her new coach, who has previously worked with fellow Belgian Kim Clijsters and Simona Halep among others.
In a chat with the NY Times, Azarenka admits what the sudden move by Sumyk after the Australian Open was a surprise.
"I will never forget what we have achieved together. I will always be grateful, but yes, it was a bit surprising for me. It was sad, nothing else. I have no anger in me.
The separation didn't end in a bad way. Then, I chose Fissette," the Belarusian said.
Sumyk, who joined Bouchard's team this week, said he did not leave for money.
"My decision to leave Azarenka for Bouchard was not due to money matters. My contract with Vika was good. I'm always looking for challenges.
"I hate comfort. When I am in a comfortable situation, it is the end of growth for me as a coach and person. I want to be the best coach. It's never the right time for a separation between coach and player.
"Our relationship was more than that of a normal relationship between coach and tennis player. Vika can improve with a new person by her side," he added.