As an author, the relationships you build with your agent and editors is crucial. It's always easier to work through a rough spot with someone you can consider a friend. On the same hand, these relationships are part of a business, your business, with you in the driver's seat. When you sign with an agent and/or an editor, the hope is that it's just the beginning of a long and profitable relationship. That doesn't always happen. Sometimes relationships can go south for all kinds of different reasons.
When contracts and trust are breached, it's time to move on. To finally have an agent or get that first contract is what you've been working toward for years. Turning away from that can feel like walking away from the dream. But if it's not right, you won't be doing yourself any favors by sticking with what's not working. Relationships are important, but at the end of the day, this is a business. You need to make the call to protect your business, your brand, and your work.
I hope you never experience the sour end of a professional relationship. If you're lucky every contract you sign will be honored and you'll never have cause to doubt promises made. If you're not lucky, hopefully you'll follow these simple steps to protect yourself as a person and as an author.