Diaz is currently dating baseball player Alex Rodriguez, having previously been in a relationship with Justin Timberlake, who she recently described as a "genius comedian".
Speaking to Elle, 38-year-old Diaz said: "I think a lot of people are married to people that they're not romantic with anymore.
"I just didn't ever marry anybody that I then had to get divorced from. We break up. We move on. All I want for him is happiness. All he wants is my happiness. His isn't reliant on me, and mine isn't on him."
During the interview, Diaz spoke of how she regularly sees a therapist on whom she can "unload" her problems.
She said: "I used to be a very, very, very cynical person. I'm not a tortured person. I have been in my past but I don't like to project that. But I'm a realist. I see things how they are and it's hard to pretend that they're anything different."
Diaz can next be seen starring alongside Timberlake in Bad Teacher, which opens on June 24.
Watch the trailer for Bad Teacher below (warning: explicit content):