Hierarchical poly practitioners often negotiate strict rules of contact to ensure there are no boundary transgressions — such as loving a secondary partner more than feels acceptable to the primary partner.
Non-hierarchical polyamorists, in contrast, believe in maintaining a number of separate-but-equal relationships, which can manifest as anything from dating a few people at once to living in group marriages (a group of three might be called a "triad", while a group of four is often called a "quad").
Every polyamorous relationship relies on open discussion of rules and boundaries; there is a running joke among poly people that you always spend way more time talking about your feelings than you do having sex with your multiple partners.
Even with all the discussion, this relationship model may not work for everybody — no matter how much they might want it to.
The protocols and practices of dating, and the terms used to describe it, vary considerably from country to country and over time.