Some years ago a theologian named William Vanstone wrote a book, now out of print, that included an interesting chapter called The Phenomenology of Love.41

All human beings, he says—even people who from childhood were deprived of love—know the difference between false and true love, fake and authentic love. Here’s the difference, Vanstone says. In false love your aim is to use the other person to fulfill your happiness.

Your love is conditional: You give it only as long as the person is affirming you and meeting your needs. And it’s nonvulnerable: You hold back so that you can cut your losses if necessary. But in true love, your aim is to spend yourself and use yourself for the happiness of the other, because your greatest joy is that person’s joy. Therefore your affection is unconditional: You give it regardless of whether your loved one is meeting your needs. And it’s radically vulnerable: You spend everything, hold nothing back, give it all away.

Then Vanstone says, surprisingly, that our real problem is that nobody is actually fully capable of giving true love. We want it desperately, but we can’t give it.

He doesn’t say we can’t give any kind of real love at all, but he’s saying that nobody is fully capable of true love. All of our love is somewhat fake. How so? Because we need to be loved like we need air and water. We can’t live without love. That means there’s a certain mercenary quality to our relationships. We look for people whose love would really affirm us. We invest our love only where we know we’ll get a good return.

Of course when we do that, our love is conditional and nonvulnerable, because we’re not loving the person simply for himself or herself; we’re loving the person partly for the love we’re getting.

Keller, Timothy (2011-02-22). King’s Cross: The Story of the World in the Life of Jesus (p. 96). DUTTON ADULT. Kindle Edition.