Karrueche Tran isn’t bothered at all by her boyfriend Chris Brown‘s rumored fling with his ex girlfriend Rihanna.

Why? Because Chris and Karrueche have what is known as an “open relationship.”

As we’ve been reporting all week, Chris and Rihanna recently spent some serious studio time together, which resulted in not just one, but two collaboration tracks: the remix to Chris’ “Turn Up the Music” single and the remix to Rihanna’s “Birthday Cake” song.

“Girl I wanna f**k you right now. Been a long time, I’ve been missing your body,” Brown sings in the first line of the song, which makes you wonder who he’s talking about … though you could probably just take a wild guess.

Lyrics like that should be a cause of concern for Brown’s current girlfriend Karrueche, however, a source close to the couple says she isn’t worried about that.

“Karrueche isn’t stupid, and she has told friends that they have an open relationship,” the source told Radar Online. “She never asks him about Rihanna, ever. Chris will take several days to call her back at times, and that is OK with Karreuche.”

The anonymous source continued, “She doesn’t pressure or hound Chris, it’s just not what she is about. She recognizes that they are both young, and she isn’t going to let the fact Chris is spending time with his ex-girlfriend come between what they have.”

Karrueche and Chris were recently spotted together in Miami, and the source tells Radar that Karrueche “is clearly enjoying the attention and notoriety she is getting being [Chris Brown’s] girlfriend.”

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