Repression is indisputably a cause of troubles in Dr. Jekyll and Mr. Hyde. The repression here is that of Victorian England: no sexual appetites, no violence, and no great expressions of emotion, at least in the public sphere. Everything is sober and dignified, and you’re really not supposed to be happy. (That would somehow take away from your focus on morality). The more Dr. Jekyll’s forbidden appetites are repressed, the more he desires the life of Mr. Hyde, and the stronger Mr. Hyde grows. This is clearly demonstrated after Dr. Jekyll’s two-month hiatus from donning the visage of Mr. Hyde; Dr. Jekyll finds that the pull to evil has been magnified after months of repression.
Dr. Jekyll’s difficulty in dealing with his inner desires is meant to reflect the difficulties of society at large.