means that sometimes you cannot marry the person you want to marry, when you want to marry them. It means not always being able to sleep with the person one may want to sleep with, at one's personal convenience, if at all. At times, being a faithful Catholic means NEVER being able to marry or sleep with the person one loves. It means self-denial and taking up the cross, which is why chastity and consecrated celibacy are among the highest forms of love and martyrdom.
So many people want the trappings of Catholicism, but not the inner core of suffering and sacrifice that must accompany true belief.