
RiRi just tweeted this pic Saturday night of CB kickin' it half-naked in bed -- bare-chested with his drawers out -- then posted it for her 26 million Twitter followers.
It's the latest in their never-ending relationship saga ... as TMZ previously reported the two have been spending more and more time together in public, including Thanksgiving -- where they partied it up at the same German nightclub.
So we ask ...