Rihanna; Chris Brown Credit: Frederick M. Brown/Getty; Jason Merritt/Getty

Guess Chris Brown wasn't Rihanna's valentine. After a PDA-packed night out on Grammys Sunday (Feb. 10), the controversial pair were anything but lovey-dovey at Hollywood club Playhouse -- where they both arrived, separately, past midnight on Friday.

The "Stay" singer, 24, and Brown, 23, were "not at all on speaking terms" at the hotspot (where revelers were celebrating the one year anniversary of Popular Demand clothing) once they settled in with their respective pals, an observer tells Us Weekly. "She refused to sit with or even near him," the witness adds. "When she noticed he was there, she made a huge show of rubbing her presence in his face."

"Happy Valentines Day," Rihanna tweeted to her 28 million followers earlier in the day. "Today the day fa lovin not hatin so to cats like you and I it's just another day…" As for Valentine's gifts for Brown or any other loved ones, the Barbados beauty shared an Instagram snapshot revealing a different sort of bouquet from an unidentified admirer. "Roses are green!" she wrote beneath a photo of what appeared to be a marijuana plant, sent by an unidentified friend. "Somebody knows how to make me happy."

The scene was much different at the Grammys earlier in the week -- where the pair (four years after Brown's infamous assault of his then-love) nuzzled in their seats at the Staples Center, and were "very affectionate" at an afterparty.