The first one is a parable of a bridegroom with his groomsmen at a wedding feast. Jesus’ point is that fasting during the wedding feast is pointless. In this story Jesus is the Bridegroom, and while He is present in this world, it is a time of celebration because He is the fulfillment of their Messianic prophecies. Jesus Himself said that He came to fulfill the law (Matthew 5:17). To continue fasting with Jesus present is akin to fasting and being mournful during a wedding celebration in which the groom is present.
The other two parables, which are similar, make the same point. The first one says you don’t put a new patch on an old garment, and the second says you don’t put new wine into an old wineskin. In the first parable, if you put a new patch on an old garment, when the new patch shrinks due to washing, it will tear away from the older garment, making the tear worse. Similarly, new wine needs a new wineskin because as the new wine expands during the fermentation process, it stretches the wineskin. An old wineskin will burst under the pressure of new wine.
These two parables illustrate the fact that you can’t mix old religious rituals with new faith in Jesus. Jesus’ disciples were not fasting along with the Pharisees and John’s disciples because they were now under the new covenant of grace and faith in Christ. As mentioned earlier, Jesus fulfilled the law; therefore, there is no longer any need to continue with the old rituals. Jesus cannot be added to a works-based religion. In the case of the Pharisees, they were consumed with their own self-righteousness, and faith in Jesus cannot be combined with self-righteous rituals.