My advice is to COMMUNICATE, COMMUNICATE, COMMUNICATE. That’s the primary polyamorous mantra, but I think it applies to basically all relationships. You’re not going to get anywhere unless you know what’s going on with the other person!
Furthermore, getting a little more specific, it’s really important to evaluate what each partner needs in a relationship. “Fairness” and “equality” isn’t as important as satisfaction. Some people want the whole relationship to revolve around them, some people like talking more than listening, some people like a lot of space. I like a lot of space, and I prefer someone who doesn’t mind being called on whenever I feel like not being all self-contained anymore. And all of these relationship styles CAN be functional, if everyone knows what they’re getting into, and wants the same thing. Some people want to be the only source of income, and some people want to be supported. I think, as long as everyone is informed and on the same page, anything could be workable.