ET's Katie Krause caught up with the 39-year-old actress at Love Leo Rescue's 2nd Annual Cocktails for a Cause event and she opened up about going public with her boyfriend, Tucker Roberts, at her friend's Day of the Dead celebration earlier this month.
"I went to my girlfriend's Halloween party. Did not know there would be a photographer there, and did not know that photographer was a Getty photographer," she said of posing with Roberts, who she was first linked to late last year. "I thought it was just her photographer for her house. I had no idea."
Though she didn't exactly mean to take her relationship public, Munn ended up posting pics of her and Roberts' couple's costume -- the pair went as siblings Jesse and Judy Gemstone from the HBO comedy The Righteous Gemstones -- on Instagram.
"The day started with my stylist who helped pull all the outfits together saying, 'You have to post this,'" Munn recalled of her decision to post the photos. "And I said, 'I don't post about it on Instagram.' And she's like, 'But it's just so good!' And I asked him and he was like, 'Well, the costumes are really good'... I needed to have Jesse Gemstone with me [for the photo] because my outfit on its own wouldn't really make sense."
Despite initially being uneasy about getting personal online -- and telling ET that there will "probably not" be more photos of Roberts on her feed -- it ended well, as Munn became friends with Edi Patterson, the actress whose Righteous Gemstones character she dressed up as for the party.
"It actually turned out really great because Edi Patterson and I... started following each other and now we're texting and now we're friends," she said. "... At the end of the day, I became friends with Edi and I'm super excited about that. It was worth it."
With her relationship blossoming, a house full of pets and new career opportunities on the horizon -- she just sold a series to Amazon that she plans to produce -- Munn is perfectly content in her life and revealed that she's unsure if kids and marriage would ever fit into the picture.
"I have two dogs, two cats, so that's a lot just with the animals. I don't have kids. I mean honestly it's a lot. I can't imagine," she admitted. "... I've really come to a realization with myself that I'm already in my happily ever after. And if I want to have kids or want to get married then I'll do that, but it has to add to my life, you know? Everything has to add to my life."
"I already love my love as it is. I'm excited about anything that might come my way, but I've already reached the pinnacle for me, what I think happiness should look like," she continued. "I've got amazing girlfriends. I've got my pets. I've got my career. I'm really, really happy. Anything else that wants to come into my life has to add."
Of Roberts, Munn added that her beau "loves, loves, loves animals," which is why he chose to join her at Love Leo Rescue's event.
"There are so many amazing animals out there that are shelter pets, that are rescue pets... Any kind of specialty dog, there is a rescue place for them," Munn said of why she personally supports the cause. "And there's so many dogs that need homes -- and so many cats and animals -- and places like Love Leo Rescue, they dedicate their whole life to helping these little animals that have no one."