"It's always sad when things like this end, and we remain friends,” Phifer tells PEOPLE. "I wish him the best in his future and all of his endeavors. He's one of the most talented people I've ever met."

Phifer was spotted on the red carpet sans her engagement ring at an "Evenings in Vogue" event on Thursday night in New York, where her clothing line, Ghita, was featured.

"They'd been having problems," a pal of West's says. "Kanye is really focused on his show; he's putting everything into the show right now. Alexis is a nice girl, but Kanye has been going through a rough time. They hit a rough patch and for now they've split."

According to the friend, Phifer and West, both 30, had been spending less time together in the last few weeks as the Grammy-winning star prepared for his nationwide "Glow in the Dark" tour. "I haven't seen [Alexis] around at all the last few times I’ve seen him recently," the friend added.