It is too complex to quantify so simply. For each person it has a different meaning. For two people love is not the same animal. If you can successfully coexist, if you needs are met, then you are given a passing grade. For some people it can be physical and others more contemplative. Rarely do you find any non caustic mix. Something meant to last.
It takes a special type of person to endure, we all weren't build that way. Some of us are more high maintenance than others. Some have an insatiable wanderlust. I think most fill up their buckets with rules and anecdotes, experience so you know the dance. No one really knows though, it is still a point of awe and wonder trying to make sense of it. Maybe just accepting what we have and leaving it at that.