The idea that keeping your loved ones ignorant of your heroic identity helps protect them is hypocritical, especially in the usual superhero context where the same people interact regularly with both the civilian and superhero identities. Villains are just as likely to capture and torture them either way, since the villains don't know in advance whether they know the identity or not. So keeping them in the dark won't spare them from torture, it'll just spare the hero from being discovered. It's something a hero does to protect oneself, not one's family and friends.
If anything, the loved ones would be safer if they did know the truth, because then they'd know of the potential threat to their safety and be able to prepare for it. As a rule, ignorance never makes people safer, just more vulnerable.
I've recently started watching one of the various Ultraman series from Japan, and I don't understand why the hero, a member of a military organization that fights the same monsters Ultraman does, hasn't told his teammates that he's the guy who turns into Ultraman. You'd think that would be a valuable thing for his team to know, and they could work together better if he weren't hiding his abilities from his own teammates and commanding officers. I don't see any good reason for them not to know. Since they're fighting monsters all the time anyway, it's not like they'd be in any greater danger than they already are. (The only clue I've gotten is an episode where a scientist with the organization proved all too eager to take a friendly alien to his lab and dissect it.)
Similarly with the various early Kamen Rider series where the Rider keeps his identity secret from most of the teammates he works with in both identities as they fight the evil organization -- even though the evil organization already knows exactly who he is! Why keep it secret from your allies but not your enemies? That's totally backward!