A successful relationship requires either:
- you’re low on Maslow’s hierarchy (lots of menial tasks to do, not much free time or slack in life)
- each partner is the other’s top priority, even above children
Without fulfilled Maslow’s hierarchy, it’s easy to not care so much about the quality of the relationship and focus on securing base needs by cooperating. Once you have those, cooperation isn’t so important and there’s slack in the system to pursue other pleasures, so the relationship quality needs to be high.
If you’re not each other’s top priority, that can work for a while, until the top priority isn’t aligned with the relationship anymore. For example, typically children will be the top priority. But once they’re grown, the couple can quickly grow distant and the relationship can deteriorate. If couples had the choice to separate or pick new partners (without any of the societal/religious consequences of divorce), they probably would.
Another example is if both people are really dedicated to a company or cause. Easy to cooperate on life things so you can both spend lots of time on it. But once there’s a slight misalignment on that goal, it’s very easy to want to split.
Making each other top priority means that enriching the relationship is the number one thing you want to be thinking about and cooperating on. The relationship is finally an ends unto itself. That seems like the only stable relationship configuration…