"Maybe that's part of my problem, is that I like the action, I like the chase -- I like all that stuff," he acknowledges. "I think it's genetic. I think it's primal for us to have that. There's certain people that you see and you just want. It's not always the most beautiful person, there's something that happens... and often times, those people that you have that for don't have that for you."
During the candid chat, Duhamel also looks back on his relationship with 43-year-old Fergie, and admits that he was uncomfortable with all of the attention they received as a couple.
"It had nothing to do with how much I loved her but I wasn't ready for all of that," he admits. "I still get, 'Oh my God, you're that guy, you're Fergie's husband'... it took me a long time to get past that. I don't know if it was my ego or what. I was like, 'I'm a person too. I'm not just Mr. Fergie.' But I learned to just find it endearing. You know, we were together for a long time and I just laughed it off."
Still, the actor insists that Fergie's star power wasn't what ended their marriage, after Shepard, himself, admitted it initially bothered him that his own wife, Kristen Bell, earns more money than him.
"Yeah, of course, I mean she made a lot more money than I did, but again, it's not really about that," Duhamel shares. "At the end of the day, I'm always going to have her back. It was tough, the public part of it wasn't an easy thing to go through, especially the breakup."
"I don't know if people were rooting for us or not, but there's something sad about that because you want to root for people to stay together, you know?" he adds. "And once you get past that and not really give a s**t what people think and just focus on the child... It just didn't work and at the same time, I really don't care anymore. ... What really matters is that we are united in raising our son. That's all I really care about."
Clearly, Duhamel and Fergie are still on great terms.
“Fergie and I had a great relationship," he says. "I love that girl and I always will. Unfortunately, we didn’t work. But I will always have her back and she is the mother of my baby. She's awesome."