Nick Offerman (L) and Megan Mullally have written a book about their relationship. File Photo by Jim Ruymen/UPI | License Photo
Oct. 1 (UPI) -- Celebrity couple Nick Offerman and Megan Mullally are sharing details about their longtime romance.
The 48-year-old actor and 59-year-old actress discussed their relationship Monday on Good Morning America while promoting their book, The Greatest Love Story Ever Told: An Oral History, which debuts Tuesday.
"It's one thing to be in love and love someone, and it's another thing to like them. And I just really like him," Mullally said of Offerman.
"I like listening to him talk. I think he's funny; I think he's interesting; and he's a great person. He's a great man. He treats me like a queen, he does."
Offerman and Mullally celebrated their 15th wedding anniversary this year. The couple met during rehearsals for a play in Los Angeles.
"We've never been apart for more than two weeks. I think it's very helpful," Mullally said.
"We're lucky that we found each other," Offerman added.
The Greatest Love Story Ever Told gives readers an intimate and humorous glimpse into Offerman and Mullally's relationship. Offerman said in an interview with Entertainment Weekly published Monday that it was "comfortable" working with Mullally on the project.
"It's strange having a pleasant and successful domestic relationship. We're lucky enough to continue enjoying each other. It's that simple," the actor said.
"We're just a couple people who like doing puzzles together. When we do things -- whether it's onstage or onscreen or record a book together in bed -- it's pleasant and comfortable. We feel very lucky that we're able to do that, and that it can be a source of inspiration for people."
Offerman is known for playing Ron Swanson on Parks and Recreation, while Mullally portrays Karen Walker on Will & Grace. The pair have collaborated on a number of projects, including the 2012 film Smashed.
Longest celebrity relationships
Ron Howard (L) and wife Cheryl Howard arrive for the Vanity Fair Oscar Party in Beverly Hills, Calif., on March 4, 2018. Ron and Cheryl Howard got married in 1975 after their first date in 1970. Photo by Christine Chew/UPI | License Photo