Bookies can start accepting bets on whether such an 'open' marriage can survive or end up in divorce eventually. This at-first-glance amusing socio-philosophical question (on the viability of open marriages and/or polyamory) can suddenly become a painfully personal emotional issue for everyone, eg. if your gf / bf / wife / hubby ever suggests it. My take : at a soul level, every soul certainly has many lovers across many lifetimes and thus polyamory is indeed natural in the extraphysical (or 'spirit world'), but during intraphysical incarnation, the nature of which is to experience reality in a dense physical way (ie. a soul's long term existential programs is planned & written into the individual existential programs for each individual physical incarnation or lifetime, exactly as how an undergraduate's 4 year academic learning needs is planned & written into the modular curriculum for each individual semester), which (for almost all human souls and incarnations) includes a period (if no breakups or divorce, then for this entire lifetime) of monogamy and monoamory to fully explore, develop and experience that relationship with your loved one in a deeply special and intimate way. Thus physical incarnational (think about it, each physical lifetime is actually pretty short anyway, blink of an eye) monogamy and monoamory actually serves an important karmic purpose, to as fully as possible focus your personal love on 1 special person (would you more fully enjoy watching one movie at a time, or 2 movies at the same time?) so as to allow you to experience such a mutually chosen relationship in the deepest, most intimate way possible. In other lifetimes, you may choose other willing partners, though all souls will (over lifetimes) develop additionally special relationships with a few other souls, and (as is often the case) choose to marry him/her again lifetime after lifetime. But polyamory, similarly to LGBT, is a personal choice between mutually consenting adults, there is no right or wrong (morality is an illusion, there is only legality, ethics and cosmoethics). It's just that in physical incarnation, monogamy and monoamory best serves the personal, karmic and emotional needs for the vast majority of incarnate humans.

http://singaporeseen.stomp.com.sg/this-urban-jungle/spore-wife-sets-hubby-up-on-tinder-dates-and-he-does-the-same-for-her