A source tells ET that the country crooner made sure to involve Stefani's three kids -- Kingston, 14, Zuma, 12, and Apollo, 6 (whom she shares with ex-husband Gavin Rossdale) -- "every step of the way" in his engagement plans.
"Blake is very close to Gwen's boys," the source says. "They talked it through and Blake made sure they were part of the excitement! Blake had a custom-made engagement ring. He knows the designer and has used them in the past to make bracelets for Gwen."
As for the actual proposal? Shelton took the traditional route by making sure to get approval from Stefani's father.
"Blake's plan to propose to Gwen began by asking her father for her hand in marriage. Gwen is very traditional so he truly felt that asking her father for approval was the proper thing to do," the source adds. "And her father adores Blake. Gwen has been ready to tie the knot for a long time and Blake knew this was the perfect time."
ET reported on Monday that Shelton, 44, proposed to Stefani, 51, the weekend of Oct. 17. in Oklahoma, where the country star has a home. A second source explained to ET why, after five years of dating, Shelton felt now was the right time to get down on one knee.
"Blake has been the one who wanted to take it slow in the beginning but recently he decided it was time. During the pandemic, they’ve had lots of downtime together and he truly saw the importance of spending life with the person you love," the source said. "Gwen takes marriage very seriously and was disappointed that her first marriage [to Gavin Rossdale] didn’t work out. She wasn't in a hurry because she wanted to ensure Blake was ready."
"They both live incredibly busy lives and have managed to make sure they work together and spend as much time as they can together," added the source. "The pandemic has given them both the time they needed to slow down and just appreciate and love each other."