Recipe For Magical LoveThe fact is (well, really the opinion, but don't worry about that) most people are not in healthy relationships.
I'm not saying most married people, I'm saying most people in relationships, dating, co-habiting, married, whatever.
There is no magic to this: getting two random people that have no linkage to each other, genetic or otherwise, to get along perpetually is HARD. Sure, it can be eased by various things, such as lust/chemistry, intellectual stimulation, and so on, but at the bottom of it all there must be altruism attached.
Let me explain a bit more clearly-- You must love someone with all of your heart-- irrespective of how they love you. We've all been in situations like that where we seem to be putting more into the relationship than the other party, or in other words, "I love YOU more." In its extreme, that is known as unrequited love. But that of willingly loving someone infinitely, without regard to how they love you, is necessary but not sufficient for a true love.
The magical part happens IF AND ONLY IF your partner feels this same sort of love towards you. So simple. And then you're on the mountain High. Otherwise, you will still experience some of the grandeur of love, but it will ultimately drain you as your effort is not matched.