The Pharisees question why the disciples of John the Baptist fast and those of Jesus do not. The inference is that this is a veiled criticism given that the Pharisees fast twice weekly and also on the prescribed days of fasting. In response Jesus uses the image of a wedding feast. Wedding celebrations in Palestine lasted a week and it would have been regarded as rude the hosts and married couple if a person fasted and did not join in on the feasting.
In the Old Testament, God the Father identified himself as the divine husband of Israel and Jesus in the New Testament as the divine husband of the Church and so Jesus compares his presence among us as a wedding feast.
With the coming of the Kingdom of God in the person of Jesus, a new reign of joy and not penance is inaugurated. Fasting and penance will recommence for the disciples and members of the Church after the coming of the Holy Spirit at Pentecost when the Church is born.
Quote from St Leo the Great on fasting
“The merit of our fasts does not consist only in abstinence from food. There is no use in depriving the body of nourishment if the soul does not cut itself off from sin and if the tongue does not cease to speak evil”