The single most important thing when looking to get into a relationship of any nature is to come from a mindset of abundance, not scarcity. A relationship driven together by a desire for comforting safety in the sense of "we both know we can't do any better, you're the best I can get, let's implicitly restrict each other" is not a healthy relationship. It's coming from a place of fear and scarcity. The ideal relationship is one where you're living an abundant life, and you choose them. It comes from a place of freedom, love and choice. Sometimes when people talk about "intimacy" they really mean control, safety and restriction. Open relationships (even with the right person) when experienced in this mindset can seem lacking because we're uncomfortable with the freedom of our partner and don't feel secure in our OWN freedom.