My experience is that 99% of all "I'm not Catholic anymore" types, i.e. ex-Catholics, become ex-Catholics because of some MORAL issues. Not for theological reasons, not because they actually "saw the light" about the errors of the Church or the truth of "Bible" religion. In fact, the more militantly anti-Catholic the ex-Catholics have become, you can be completely certain that some moral issue was behind it.
-- divorced/remarried
-- issues with "confessing to a man" (too embarrassed to confess and rationalizing why they shouldn't have to)
-- were ɧoɱosɛҳųαƖs
-- various sins of the flesh that they don't want to give up (fornication, adultery)
In fact, I've called them out on public forums before. Some ex-Catholic would rip on the Catholic Church and I would post something like, "So, tell us the truth, you're either divorced/remarried or a ɧoɱosɛҳųαƖ or didn't want to go to Confession." Most of them will reluctantly admit one of these to be the case.