Wait what am I missing? Catholic priests who were married before becoming priests is a thing.
Our local priest is married with kids and grandkids.
Our local priest is married with kids and grandkids.
Since, IIRC, the 1200s (may be off by a couple centuries), there has been a practice (not a doctrine) prohibiting ordination of married men in the Latin Rite of the Catholic Church.
Because this is a prohibition but not a doctrinal invalidity, it does not invalidate otherwise-valid ordinations (i.e., by Bishops holding valid apostolic succession), and the prohibition was never applied to the Eastern Churches that were at the time (Inthink the Maronite Church was) or later came into union with Rome. There is also now a special exception allowing (with individual permission, not automatically) married Anglican priests who convert to Catholicism and are otherwise eligible for ordination as Catholic priests to be ordained in the Latin Rite despite being married. So it is possible to encounter married priests in the Latin Rite (Western) Catholic Church, but the door is not generally open to married men becoming priests.
Nor are they expected to refrain from sex within marriage, which may be what you mean.
Of course, if a married Eastern Catholic priest decided to join the Latin Church with the rest of his family, this could happen too.
But generally, a married man will want to discern the diaconate, as the priesthood will simply be out of the question, except in these exceptional circumstances.