As Pope Paul VI wrote, it is a "total and perpetual continence for the sake of the Kingdom of Heaven" that "shines forth as a light that never sets."
First, a crucial clarification: Celibacy is not part of the substance of the priesthood (dogma), but a discipline of the Latin Church. Eastern Rite Catholic Churches ordain married men. However, Sacerdotalis Caelibatus argues that this discipline is not arbitrary. It is rooted in the very mission of Christ and the Apostles. It is a law that serves a higher purpose: total availability for the Kingdom of God.
Next time you see your parish priest, remember: He has not said "no" to love. He has said a much more difficult, and beautiful, "yes."