Perlin, 37, is in the process of moving out of Couric's Upper East Side townhouse in New York City. The former "CBS Evening News" anchor -- whose husband Jay Monahan passed away from colon cancer in 1998 -- met Perlin in 2006 at a cancer research fundraising event at the Louis Licari Hair Salon.
A Couric pal tells Us she initiated the breakup. "Brook's a nice guy, but it was inevitable because they had different priorities and perspectives, and their age difference made it a challenge, too."
"Katie is someone who is incredibly versatile and accessible and in high demand and he just couldn't keep up," the Couric pal adds. "He had a little more trouble in the relationship. So she's available and back on the market."
Despite their recent breakup, a Couric pal tells The New York Post's Page Six they remain amicable. "Brooks is a great person and a real gentleman; he and Katie enjoyed their time together. But after five years, they have decided it was time to go their separate ways."