"Big Tony... He went home. He wasn't cool with the lifestyle. I didn't break up with him. It was a mutual thing," said Bowersox during an appearance on Ryan Seacrest's KIIS-FM radio show that occurred after Wednesday night's live finale that saw her finish as the runner-up to Lee Dewyze.
"I'm a little sad that he did it on performance day, but then again it set that fire to my belly."
The 24-year-old from Toledo, OH added she's "cool" with the mutual decision she and Kusian came to.
"We're both logical, grown adults. He's a small town guy and that's fine, I'm a small town girl, but I want this," she explained to Seacrest.
"I want this more than anything, this career, this lifestyle. I didn't think he was up for it. He didn't think he was up for it."
Bowersox said she was "really hoping" Kusian would still be in attendance at the live finale, however he decided to leave Los Angeles and begin driving back home immediately.
"He's in Colorado, I think, driving back to Ohio," she told Seacrest.
American Idol judge Kara DioGuardi, who also participated in the interview, praised Bowersox's Tuesday night performances as being "so emotional."
"Your voice, it just took you to a whole other place," added DioGuardi.
"I had a hard morning," responded Bowersox, refering to her split with Kusian.
"But you know what, it's so great that you can release that on stage," said DioGuardi.
Seacrest added that Bowersox's American Idol experience has "got to be tough for everybody around" her.
"This is something you've always seen yourself doing to a degree," he said. "For them, it's just not what they pictured. So it really is hard for people to adjust. But listen, you are so passionate about what it is that you do and you're so you when you're on the stage singing, it's really incredible to watch."
"There's a difference between who you are at home and there's a difference between who you are on a stage," responded Bowersox. "To me, I'm just me. There's no difference to me. I can't pretend. I just can't."
The 39-year-old DioGuardi -- who got married last summer -- told Bowersox that it's difficult having romantic relationships when you're focused on a music career.
"It's hard to find that match, someone who allows you to be you and is secure enough in letting you be you. You're still young, you have a life in front of you and you have to do your music. It's not a choice for you," said DioGuardi.
"It makes you whole and it makes you feel good about yourself. If somebody can't hang with that -- I'm sure he's a lovely guy -- but this is your journey. You can't get off it."
"He's been great through this whole thing," replied Bowersox. "I'm not made at him. I get it. Some people can hang with it, some can't. I'm fine."
Both Seacrest and DioGuardi urged Bowersox to talk with Kusian once the American Idol machine slows down.
"Once the dust sort of settle from all the activity this week, you should definitely try and have a conversation with him again," advised Seacrest.
"We're going to be friends for a long time," said Bowersox.
"I think to make a decision during these few days..." continued Seacrest before being cut off by DioGuardi.
"It's hard. You've got to let the dust settle," said DioGuardi.
"I told him that too," she said. "So we'll see. He'll be alright."