It's a little late to change their minds. Heather suddenly finds herself getting cold feet on her wedding day in Married at First Sight's Tuesday, August 2, episode, as seen in Us Weekly's exclusive sneak peek.

The FYI unscripted series' preview clip shows the 32-year-old flight attendant in her wedding gown just before meeting her husband for the first time at the altar.

"I feel very nervous, but I am tired of being single, and I would really love to share my life with someone," Heather tells the camera. "I'm here today, really, to find a life partner. I feel like I'm really willing to get married at first sight, especially considering all my past relationships have failed. I love my job, I like my lifestyle, but I'm kind of missing that component of love from a man, a spouse."

As the moment of truth approaches, Heather's mind-set quickly changes.

"Now everything is rushing at me, and I just feel overwhelmed," she says. "This is a totally unknown situation, and I start panicking. What am I doing? Like, this could be really, really, really bad. Oh, my God — what am I doing?"

In last week's season 4 premiere, viewers met Heather and husband-to-be Derek, a 35-year-old account executive. This season's other couples are Tom and Lillian, and Nick and Sonia. Last season was a tough one for the series, as none of the three couples remained intact.

Watch the clip in the video above. Married at First Sight airs on FYI Tuesdays at 8:30 p.m. ET. 

Can't get enough of Us? Sign up now for the Us Weekly newsletter packed with the latest celeb news, hot pics and more!