A throuple relationship can be completely equal among the three parties. This equality is more common when all three of them find each other around the same time. However, if you’re in a long-term relationship already, and want to consider adding in a third person, there might be a hierarchy. Your long-term partner might become your primary partner, and the third person might become a secondary partner. Though, your relationship is unique as you build it as per your choices. So, you don’t need to follow any strict guidelines.