i checked the Catechism to see what it said about Vocation. The word “Vocation” is used dozens of times, and many of the discussions of Vocation could apply to any member of the human race, or any member of the laity regardless of marital status. It seems like the Church currently takes a very broad approach to the concept of man’s “vocation”, so the discussion of single people not having a vocation would seem superfluous, as they obviously are called to the “vocations” set forth in the Catechism that apply to all people or all lay people.
Here are some samples (the capitalization is in the original, I’m just cutting and pasting):
MAN’S VOCATION LIFE IN THE SPIRIT
1699 Life in the Holy Spirit fulfills the vocation of man (chapter one). This life is made up of divine charity and human solidarity (chapter two). It is graciously offered as salvation (chapter three).
826 Charity is the soul of the holiness to which all are called: it "governs, shapes, and perfects all the means of sanctification."297
If the Church was a body composed of different members, it couldn’t lack the noblest of all; it must have a Heart, and a Heart BURNING WITH LOVE.
and I realized that this love alone was the true motive force which enabled the other members of the Church to act; if it ceased to function, the Apostles would forget to preach the gospel, the Martyrs would refuse to shed their blood.
LOVE, IN FACT, IS THE VOCATION WHICH INCLUDES ALL OTHERS; IT’S A UNIVERSE OF ITS OWN, COMPRISING ALL TIME AND SPACE - IT’S ETERNAL!
THE LAY FAITHFUL
897 "The term ‘laity’ is here understood to mean all the faithful except those in Holy Orders and those who belong to a religious state approved by the Church. That is, the faithful, who by Baptism are incorporated into Christ and integrated into the People of God, are made sharers in their particular way in the priestly, prophetic, and kingly office of Christ, and have their own part to play in the mission of the whole Christian people in the Church and in the World."430
The vocation of lay people
898 "By reason of their special vocation it belongs to the laity to seek the kingdom of God by engaging in temporal affairs and directing them according to God’s will… It pertains to them in a special way so to illuminate and order all temporal things with which they are closely associated that these may always be effected and grow according to Christ and maybe to the glory of the Creator and Redeemer."431