Do blocked people know they are blocked?

No notification is sent when you block someone, so they aren't told directly.

They can still work it out, though. If they try to visit your profile, it's replaced with a notice saying they've been blocked, and any existing conversation between you shows a notice that they can't send a message because they're blocked.

What if they blocked me?

If someone blocked you and then visits your profile while logged in, they cannot view it. Instead, they see a notice saying You have blocked [username], with your username shown in place of [username]. This refers to the block they placed on you; it does not mean you blocked them back.

They would only see a notice saying they are blocked if you separately block them.

Why did someone block me?

Blocking is a member-to-member choice. Only the person who blocked you knows why, and Cuddle Comfort cannot explain or override that decision.

Blocking also affects visitor history. When either member blocks the other, visitor-history rows between the two of you are removed from both visitor lists. If the block is later removed, those rows are restored.

One limitation: if you haven't also enabled the separate Block Public Visitors setting, a blocked member who knows your profile's direct URL could still view the public version of it while logged out. For more on that setting, see How do I make my profile private or block public visitors?.