Question for book readers

Did Jeremiah actually cheat on Belly? I haven't read the books, but alot of people said that Jere cheated on Belly while they were in a relationship. However, some people are also saying that this happened after Belly broke up with Jere after a bad argument.

If that's the case, then is that actually cheating? I can understand why Belly would be hurt that Jere slept with someone else, but I don't think rebound sex is the same a cheating on your partner.