Why did juno curse echo?

Juno cursed Echo because she was a nymph who distracted the goddess with her chatter, allowing Zeus to escape Juno's wrath during his infidelities. As punishment, Juno took away Echo's ability to speak independently, forcing her to only repeat the last Words spoken to her. This curse ultimately led to Echo's tragic fate of unrequited love for Narcissus, as she could only echo his Words without expressing her own feelings.