The expectant mom says she was first attracted to Kroy's "cute butt."

on Jul 24, 2013 - The Dish

Less than three years ago, Kroy Biermann was a single guy whose life revolved around his football career. Now things are a little busier for the 27-year-old Atlanta Faclon. He's married to RHOA star Kim Zolciak and the father of four—with another kid on the way!

Soon after the pair wed in November 2011, they welcomed Kroy Jr and a little over a year later Kim gave birth to their second son Kash Kade. On an episode of Don't Be Tardy..., last month Kim announced that they are expecting yet again.

So when did Kim first fall in love with Kroy—and was she looking to expand her brood even more at the time? Not really.

"I had my daughters, and so if I never got married and didn't have any more kids I was kind of OK," she tells E! News. "It wasn't like I was out there going, ‘Oh my god, my time clock's ticking, I gotta have children and I gotta do this.' I didn't have that."

PHOTOS: See Pictures of Kim Zolciak's Best Moments.

Kim also reveals what first attracted her to the football star. "When I saw his butt, I have never in my life seen a butt like that," Kim gushes (and yes she really does call her hubby "tightass"). "But again I didn't really think anything. I just thought, ‘Wow he's got a really cute butt and a million-dollar smile.' I love big wide smiles. His energy was great, but 'OK, I'm filming, I'm working, I gotta go' and that was my mindset."

What really won Kim over was the way Kroy treated her girls, Brielle, 16 and Ariana, 12. The 35-year-old explains that Kroy was completely genuine and never tried to win their approval to woo their mom. They approved of their mom's new beau instantly.

In fact Kroy developed such a tight bond with Kim's daughters that he also adopted them—and he reveals what made him take on that role. "Before Kim and before the girls and before the boys, I lived a pretty regimented life," he confesses. "I'd wake up, eat breakfast, go to work, come home...it was pretty normal. Now, my house isn't going to be as clean as it was before, but it's not important. Those things are not important and it's all about prioritizing and understanding."