As the pair excitedly picked a date—Nov. 18, 2017—and booked the church where Ryan's parents Jen and Larry once wed, Bookout gave her wholehearted endorsement. "They have a very healthy relationship," she told MTV News. "I think she's very understanding and supportive of him—she's a really good friend to him, but she also has enough of a 'I'm not going to put up with your s--t attitude.' It's the perfect balance for what Ryan needs in a partner."

That trait was tested several months later. When Mackenzie discovered what she called Ryan's "strong addiction to heroin" last spring, she phoned Nashville's Addiction Campuses "immediately." Shocked and seeking "backup and guidance," she says, "I spilled my guts to them about what was happening." And, with the help of an interventionist, she formulated a plan. "The interventionist told me how I needed to decide my boundaries," she explained. "I distinctly remember him saying, 'Would you give up if he was dying?' I said no. He reminded me that if Ryan didn't get help, he would die."

With that in mind, she established her personal deal breaker—if he didn't agree to get help, she was out—and poured her heart out in a letter. "It spoke of our good times, our first date, our boys growing up and how I wanted him to be there for future times," she recalled. "It reiterated how much more he loved his family than his drug of choice. When he was ready to get help, I would be there. But until then, I couldn't do that." Tossing the letter on a counter, she grabbed her Cavalier King Charles Spaniel puppy Chance "got in my mustang and left. Then the waiting game started."