Hayden first met Ukrainian boxer Wladimir Klitschko in 2009 at a book launch party for their mutual acquaintance Diana Jenkins. They began dating soon after that. In May 2011, Hayden announced that the two had split, citing the struggles of long-distance dating as the root cause. However, in April 2013, Hayden confirmed that she was back together with Wladimir. They announced their engagement later that year.

On Dec. 9, 2014, Hayden gave birth to their daughter, Kaya Evdokia Klitschko. Kaya was born in Hawaii and weighed 7 lbs., 14 oz. “I’m thrilled that I am having a girl first because I feel like I know a lot about raising a strong woman,” she told Hello! magazine shortly before Kaya was born. “I feel very empowered myself and I think my daughter will, too.”

In October 2015, Hayden stated that after Kaya’s birth, she had experienced postpartum depression. In October of that year, she voluntarily checked into a treatment facility in order to get help with her postpartum depression (via Us Weekly). In May 2016, she announced on Twitter that she was once again seeking treatment for postpartum depression, which she said had “impacted every aspect of [her] life.”

In 2018, Hayden and Wladimir broke up. Hayden’s mother, Lesley Vogel, told Radar Online at the time: “[I] think there are a lot of changes going on in her life. But I think they’re positive changes. And I think that she’s taking some time.” Lesley said that Hayden and Wladimir were on good terms despite their breakup.