@Depressed Knoll
People focus too much on Rarity’s “girly girl” to Applejack’s “tomboy”. They’re both very hard workers, value their friends and family, and want what’s best for others, including each other. Rarity obviously trusts Applejack’s judgement enough to let her be a judge on fashion designs (Yeah, that episode is a mess, I’m just making a point) and they’ve been shown that they can in fact cooperate with each other with little to no problems. Rarity may not like it if Applejack pushed her to do dirty work, nor would Applejack like it if Rarity tried to force her into wearing some frilly dress, but
who would like someone being too pushy about their interests? Rarity sometimes gets messy, Applejack sometimes dresses very nicely. It’s not like they’d be arguing all the damn time. They’ve come a long way since “Look Before You Sleep” and have a better understanding of each other, as well as everyone else in the group. Hell, Applejack was the only one comforting Rarity after that incident in Magic Duel, as one example.