There are two aspects of man's existence which are the special province and expression of his sense of life: Love and Art.
Only Ayn Rand can make something like love sound so clinical. However, I encourage you to rend the chest and discover the heart of Rand's theory: I find her thoughts on love more graceful and romantic than a whole cache of Hallmark cards. This not to say I necessarily agree with Rand's politics, economics, or social theory. What I find most appealing about this is the acknowledgement that blindness in love, so-called "evil consequences of mysticism", really leads to tragedy. We are more apt to be guided by whim in love than in any other area of our lives. And whim, by definition, is fickle, untrustworthy, and absent direction. These are not descriptors I would want attached to a life partnership. Therefore, Rand suggests applying reason to your love.
Figure out why you love someone: Attraction is chemical, so that does not factor. Examine your partner's "sense of life". While this term suffers from Rand's own mysticism, and "is not a reliable cognitive guide", I take it to some concrete extremes:
"It was a miserable machine, an inefficient machine, she thought, the human apparatus for painting or for feeling; it always broke down at the critical moment; heroically, one must force it on."