Does afflict damage happen if the attacking creature is blocked?

Afflict is a triggered ability that reads: "Whenever this creature becomes blocked, defending player loses life equal to its afflict value." Wait — actually that is exactly backwards from the question. Afflict does trigger when the creature is blocked, not when it goes unblocked. So the answer is Yes: Afflict damage (life loss) happens precisely because the creature was blocked.

According to CR 702.130a, Afflict triggers whenever the creature with Afflict becomes blocked. This trigger goes on the stack during the declare blockers step, after a blocker is assigned to it. The defending player then loses the specified amount of life, regardless of what happens to the creatures afterward.

This means even if the blocking creature destroys the attacker before combat damage, the Afflict trigger has already resolved and the life loss still occurs. Afflict is designed to punish the defending player for blocking — you lose life either way, whether you block or let it through.

Concrete example: You attack with a 2/2 creature with Afflict 2. Your opponent blocks it with a 3/3. As soon as the block is declared, Afflict 2 triggers. It resolves and your opponent loses 2 life. Then in the combat damage step, the 3/3 deals 3 damage to your 2/2, destroying it — but the 2 life loss from Afflict already happened.

CR 702.130b confirms the life loss is not combat damage; it is simply life loss from the triggered ability, so it cannot be prevented by effects that only prevent combat damage.