We're told Karrueche -- Chris' other on-again/off-again girlfriend -- was invited by Chris himself to the party (thrown by ZING Vodka and Black Pyramid) to celebrate Chris turning 24. Our sources say the two still talk often and hang out, and that she still cares about Chris very much.
Here's to hoping some combination of these crazy kids can make it work.
Chris Brown's recently-dumped ex Karrueche Tran still believes she has a future with the singer -- in fact, Karrueche is telling friends, she's not gonna stop trying to get with CB just because Rihanna's back in the picture.
Sources close to Karrueche tell TMZ, she was hurt when Brown gave her the axe a few weeks ago ... but she never stopped loving him -- and now, she is on a mission to get him back.
We're told Karrueche got used to a certain level of celebrity while dating the singer, and she's not ready to "go back to being basic" -- even if that means messing around with Brown, while he's messing with RiRi.
Eventually, we're told Karrueche hopes to edge Rihanna back out of the picture.
Case in point -- Karrueche and CB were spotted hanging out together Monday in Burbank, CA ... two days after Rihanna and CB were spotted together in L.A.
As we previously reported, CB broke up with Karrueche earlier this month -- citing RiRi as the reason -- saying, "I love Karrueche very much but I don't want to see her hurt over my friendship with Rihanna."
She's single ... and it appears Chris Brown's ex-GF is ready to mingle -- 'cause Karrueche Tran hit up the L.A. club scene this weekend on a serious girls' night out.
Tran and two of her girlfriends rolled up to Greystone Manor in Hollywood in a tricked out blue Porsche Panamera shortly after midnight Monday morning.
As we previously reported, Tran was pissed when she saw Brown's bizarre breakup video statement ... in which he questioned if it's possible to love two people at once.
Karrueche wasn't in the mood to test out the theory for herself last night -- she and her friends left the club shortly before 2 AM without any dudes.
Sources close to Karrueche Tran tell TMZ ... she's livid over the fact that Brown blasted their personal problems all over the internet with his ridiculous video -- in which he confesses to loving Rihanna and Karrueche at the same time.
If Chris thought the video would soften the blow of breaking up with Karrueche ... he was dead wrong. We're told KT feels Brown should have kept his feelings private and she's disappointed and hurt by his decision to broadcast their personal life.
As TMZ previously reported ... Brown announced his split from Karrueche earlier this week by stating, "I love Karrueche very much but I don't want to see her hurt over my friendship with Rihanna."
He later posted this video, claiming he has feelings for both ...
Chris Brown just released a hyper-produced propaganda break-up video ... in which he drunkenly says he loves BOTH Rihanna and his ex-GF Karrueche Tran ... and says, "I'm not trying to be a player ... I just care too much sometimes."
It seems to be an artsy-fartsy way to explain his decision to kick Karrueche to the curb after being seen with Rihanna this week.
In the footage, Brown tries to hammer home the point that he's wasted -- intercutting footage of himself poppin' champagne, partying in a nightclub and looking slouched over while smoking. At one point he says, "I'm a little drunk, so I'mma be honest ..."
It's unclear when the footage was shot ... but two hours before Brown posted the video, Rihanna tweeted, "Ain't nobody bidness..... But mine and my baby!"
He never mentions either woman by name in the video, but there are shots of both RiRi and Karrueche spliced into the 1:27 clip.
At one point he asks, "Is there such thing as loving two people? I don't know if that's possible but for me I just feel like that."
So, is this Chris being honest ... or is he trying to BS his way out of looking like a jerk who was stringing Karrueche on while banging Rihanna behind her back?
Chris Brown and Rihanna got real -- like REAL real -- by getting cuddly at Jay-Z's concert! Then Chris got REAL by dumping his GF!! Too REAL, right?
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Chris Brown has touched down in Los Angeles ... looking like he lost about 90 pounds.
Brown announced this morning that he kicked his GF Karrueche Tran to the curb because he wants to concentrate on his "friendship" with Rihanna ... and by "friendship" he means he's going to take her to Bone Town.
As we previously reported, Karreuche -- like the rest of the planet -- believes Brown has been hookin' up with RiRi behind her back for a while. Duh.
Chris Brown's ex-girlfriend ain't buyin' that Chris is "just friends" with Rihanna ... telling her peeps she's convinced they were bangin' behind her back.
We spoke to multiple sources connected to Karrueche Tran ... who tell us KT feels betrayed by Chris because he had promised her that she was the only woman in his life ... especially when she probed him about his feelings toward Rihanna.
We're told Karrueche had suspected something was up between the two of them for weeks because Chris was acting differently -- going to clubs alone, acting distant and ramping up his public appearances with Rihanna.
Sources say Karrueche told friends she truly loved Chris ... and felt that the relationship was great until Rihanna let Brown back into her life.
We reached out to Karrueche for comment -- so far, no word back.
Chris Brown says he has officially BROKEN UP with his girlfriend Karrueche Tran ... explaining, "I don't want to see her hurt over my friendship with Rihanna."
Brown just made the announcement ... saying, "I have decided to be single to focus on my career. I love Karrueche very much but I don't want to see her hurt over my friendship with Rihanna."
He adds, "I'd rather be single allowing us to both be happy in our lives."
The announcement comes after Brown and Rihanna were spotted together at the Jay Z concert in Brooklyn last night. The two had been hanging around each other A LOT lately ... and did some hardcore flirting at the MTV VMAs.
Karrueche had posted a cryptic tweet last night reading, "Bye baby."
Now it makes sense.
Rihanna and Chris Brown aren't even trying to hide it anymore -- 'cause it looks like they were getting cozy at the Jay-Z concert tonight ... and, based on Twitter, everyone in Brooklyn saw it.
A pic taken from behind RiRi and Chris at Barclays Center is burning up the Internet -- they're seated in VIP ... he's on the left, she's on the right.
No physical contact -- in the photo, anyway -- but Chris' right arm is stretched around the back of Rihanna's chair.
This reunion comes the night after Chris and Rihanna were spotted at the same table in an NYC nightclub.
They were also seen leaving the same hotel on Wednesday -- and, for what it's worth, Chris' blind-as-a-bat GF Karrueche tweeted "Bye baby" ... just a couple hours before tonight's concert.
Bye baby— Karrueche Tran (@karrueche) October 4, 2012
Apparently, Jay-Z is so powerful he can turn back time ... to 2008.