no need to couple rudder and ailerons on a Nexstar...I've taught more than 1 student on that airplane....I've never met anyone that went to that school with no flight time and learned to fly...I did see a guy go to a school, perhaps that one, but he had been flying for a while..he came back and solo'd....
the biggest thing you are learning right now is muscle memory..how much throw equals this much aircraft movement....and teaching your eyes to see the aircraft (everyone has a point in the pattern that can disorentate them)....
hang in there I'm sure you're learning at the proper rate..after all you ask this question....
if you don't couple rudder and aileron you will be a better pilot because you're using your thumbs.....
Hang in there..easier isn't always better...nothing worthwhile is ever easy...
Good Flyin