Pretty and Quack Quack do not interact very often on the show. Quack Quack doesn't seem to harbor any malice against Pretty, but she seems to have an apparent dislike towards him.
Quack Quack doesn't usually do anything bad to Pretty or get mad at her despite her rude and selfish behavior, even when she insults him. The only exception to this so far in the series is in "Let's Play Top Models" when he is part of Kaeloo and Mr. Cat's scheme to get revenge on Pretty and is one of the people cheering after she gets humiliated on the news.
In "Let's Play Marriage", the two wind up being married thanks to Kaeloo's obliviousness to the fact that everyone was against this (except Olaf, who wasn't there, and Mr. Cat, who just didn't care). Eugly was originally intended to be the bride, but Pretty took over the role because she had already bought a wedding dress and was expecting Mr. Cat to take her away from the wedding.