How can you tell if you're being set up for a smear campaign before a breakup actually happens?

Have you ever felt like you were in a relationship with someone who seemed emotionally immature? How did pet names play into that dynamic?
Is 30 days too long to wait for a reply? I recently reconnected with a boy who used to have a crush on me in our childhood, and he admitted himself that he still harbored feelings for me. But he hasn’t replied to me in a month, and I’m very confused.