Jesus was contrasting His way versus the way of the Scribes and Pharisees.
The main issue that Jesus had with some Scribes and Pharisees in the Gospels is not the Law but how the Law was applied. What happened over the centuries was that they had not just tried to apply the Law but built “a fence around the Law.” For example, the Law simply said to avoid work on the Sabbath. The “fence around the Law” decided by Pharisees and scribes then meticulously defined “work.” These decisions of men were considered equal to the Law. The sheer number of interpretations and applications of the Old Testament Laws was mind boggling and added another layer of burden on the average person unversed in such things.
In place of the yoke of the complicated interpretations Jesus invites the burdened to take the yoke of obedience to his word (love God above all else, and your neighbor as yourself).
There is no contradiction between this saying and the saying about the gate being narrow. The gate may be narrow, but it is plenty wide enough for us to fit through.