Julia is not sexually attracted to Brandon
Let's get real. She's one of the many women that doesn't want to get freaky with her guy because she's simply not sexually attracted to him anymore.
No female wants to be intimate with a guy that's begging for it all the time. It's the least attractive thing ever to be with someone that's nonstop thirsty. The reality is that Brandon restricts her too much and he's a party pooper. Julia likes to let loose and party and the fact that Brandon keeps trying to "tame her" kills her sex drive.
I honestly feel bad for her. The only thing Brandon can do is let HER approach HIM for sex. The more he asks, the less she will want to do it. It's suuuuuch a turn off and Brandon's just hyperfocused on his blue balls rather than giving his wife the space she needs to regain her sexual interest in him. It's so sad (and cringey) to watch him pressure her on TV.