Gisele Bundchen "wasn't satisfied" in her marriage to Tom Brady before the NFL star began "doing [his] part for the family".
The American football player has revealed he went through a rough patch with his wife Gisele "a couple of years ago", when she expressed her desire for him to do more for their family - including son Benjamin, 10, and daughter Vivian, seven - during his time away from his career.
He said: "A couple of years ago, she didn't feel like I was doing my part for the family. She felt like I would play football all season and she would take care of the house, and then all of a sudden when the season ended, I'd be like, 'Great, let me get into all of my other business activities. Let me get into my football training,' and she's sitting there going, 'Well when are you going to do things for the house? When are you going to take the kids to school and do that?'
"That was a big part of our marriage that I had to like check myself because she was like 'I have goals and dreams too.' "
The 39-year-old supermodel wrote her husband - whom she married in 2009 - a "heartfelt letter" to explain how she felt, and the pair even attended marriage counselling to help get their romance back on track.
And whilst Tom admits he was "resentful" over Gisele's comments at first, he has since come to realise they have both "changed and evolved over time".
He added: "Because with my family, the situation wasn't great. [Gisele] wasn't satisfied with our marriage, so I needed to make a change in that.
"She actually wrote me a letter, and it was a very thought out letter that she wrote to me and I still have it and I keep it in a drawer and I read it. It's a very heartfelt letter for her to say this is where I'm at in our marriage, and it's a good reminder for me that things are going to change and evolve over time. What happened and what worked for us 10 years ago won't work for us forever because we are growing in different ways."
Now, the couple are stronger than ever, and Tom says they both work hard to keep the balance between them.
Speaking to Howard Stern for SiriusXM, the sports star explained: "The point of a relationship is that it has to work for both [partners]. You better work on both because if you don't then it's not sustainable.
"[Things have] changed for the better because I found a wife and a woman that I saw myself with for the rest of my life and she's been an amazing supporter in everything I've done."