Hailey Bieber "really hurt" Justin Bieber early in their relationship.
The 24-year-old model and the 'Yummy' singer sparked rumors they were together in 2014 and dated before their split in 2016, and then rekindled the romance in 2018 and got married that year.
Reflecting on "one solidified moment" where things were "maybe not cool with each other", she told the 'In Good Faith with Chelsea & Judah Smith' podcast: "I did something that really hurt him and I think that maybe took that idea [of marriage] out of his mind at that point.
"I think that was obviously confusing."
Hailey didn't go into details, but she admitted she did "something very immature and stupid" which temporarily "damaged" the idea of them tying the knot.
However, she always always "held onto the idea" that things would work out, and she explained how a lot of their conversations "behind closed doors" were about marriage and children.
She said: "We were having pillow talk conversations, with him telling me my biggest goal in life is to have a healthy family.
"In my head, I'm just like, 'I just don't think that that is BS because he doesn't have to say that'.
"We always had so many conversations about our goals, where we wanted to end up at a certain age. We always wanted to be married young and have a young family and have kids young."
Meanwhile Justin, 27, revealed that during their breakup, he was focused on his faith and mental health, and he was writing about Hailey without realizing what path his life would take.
He added: "There were nights where I was journaling and talking about you, not knowing that it was you I was going to marry.
"Just praying for my wife. Just praying that God would protect her. As I knew that I was preparing myself for her, that He would be preparing my wife for me."