Such drama is about as common in other variations of relationship, including the very conventional mono- couple situation. Only the topics of difficulty, debate and disagreement differ.
What probably allows people to deal with one another up close is ... lowered expectations. Not lowered loving. Just less demands placed on one another to be EVERYTHING to one another and agree on every damn thing. In other words, we're -- the overwhelming majority of us -- difficult. At least sometimes. Even a lot of the time. Ain't nobody perfect and ain't no two people compatible in EVERY respect.
That said, it's good to be clear on what is a deal breaker for one's self. But don't get TOO picky, this is Earth and we're human. We can work things out when we want to--sometimes.