Aphi VS Theta & frats just wondering

Just wondering why Aphi is considered top sorority if Phi Delt is considered the top fraternity and they typically only do stuff with Theta and very rarely hang with the Aphi girls. Wouldn't the top frat typically interact with the top sorority? Aphi has to practically beg for attention from Phi Delt and end up mixing mostly with ADP which is considered second, sometimes even 3rd behind beta. Just curious on how that works since it is usually frats that kind of determine the rankings... but I guess a lot of Phi Delts consider Theta top but that doesn't matter? Just curious