"When he came down that morning, I was so happy and excited. He wears, like, athletic sweatpants or shorts all the time, so when he puts on the jeans and boots it's like, you know, it just warms my heart," Shelton, 47, told a reporter. "I mean, it really does to see him have a little bit of country flair to what he wears."
The "Came Here to Forget" crooner said he also bought the tot a cowboy hat, noting, "We got to get him to wear it more."
Stefani, 54, also shares sons Zuma, 15, and Kingston, 17, with ex-husband Gavin Rossdale, 58, and while the Bush singer is a present father for his boys, Shelton also considers himself a big part of their lives.
In fact, his duty as a stepdad is one of the things that prompted him to leave The Voice this year after 23 seasons.
"If I walked away from my career at this time, the only thing that I run the risk of is having regrets that I'm missing out on some more important things in life," the country superstar explained in an interview last year. "For now, that's our kids. This isn't about me anymore and never will be again."
"Even though I'm a stepparent, I take that job very seriously. The kids see me as a very important person in their life," Shelton added. "[When they ask,] 'Why isn't Blake here?' I take that stuff to heart. I've made plenty of money, but you can't buy time back. I don't want any regrets."
Nonetheless, Shelton also understands that in some situations with the kids, he needs to let his wife and her former spouse work things out.
"I've had stepparents. I think it's, in some ways, it's harder, more difficult," he noted on the Friday, November 10, episode of Today. "I try to be careful about when to step back and be smart about when to step back and just talk, but no matter what, I'm always there if I'm needed."
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While the exes are in touch because of their three sons, the guitarist confessed they don't always see eye-to-eye on parenting.
"I think you can go one of two ways — you can either do everything together and really co-parent, and see how that goes — or you can just parent. And I think we just parent," the father-of-four shared. "We're really different people ... I don't think there's much similarity in the way we bring them up, but I think that gives them an incredible perspective to then choose which pieces of those two lives they'd like to inherit and move on with and which part of themselves come out of the whole process."
Entertainment Tonight spoke to Shelton about Apollo's style.