How do you “find” sustainable love for a lifetime with a partner? 
I’m inspired and often moved by a great love story; but I don’t necessarily buy into the notion that certain people are “meant to be,” or that there is only one person out there for you. (It could happen, certainly.) What I have noticed, however, after observing human nature for a couple of decades is that there are four key dimensions of intimacy that play a huge role in an enduring love relationship where people truly do not part until death. 
These dimensions are Intellectual, Emotional, Spiritual and Physical Intimacy. Assessing a relationship through these lenses is a helpful way to, first, determine whether a potential mate is a good fit; and, second, focus your energies on necessary growth areas in your current relationship so it can become healthier. Let’s unpack them one at a time, please. 
Intellectual Intimacy. Frankly stated, two people in a love relationship need stuff to talk about! There must be some sort of shared curiosity in a particular discipline—or, at least, a cultivated appreciation of the other person’s curiosities. If one person begins to “out-distance” the other in terms of critical thinking or education, the relationship suffers. The happiest couples I know are both lifelong learners. There is no standing still in a relationship; it is either regressing or progressing. When I hear people say “we have nothing in common anymore,” this dimension of intimacy has been neglected. 
Emotional Intimacy. A commitment to giving one another the benefit of the doubt is the foundation of this dimension of intimacy, for it keeps a wellspring of good will flowing within the heart of the relationship. When combined with a commitment by each person to keep growing in emotional intelligence skills such as self-awareness and active listening, two persons can have a lot of joy together because they feel safe in the relationship. If you had to choose between intellectual intimacy and emotional intimacy, choose the latter—but don’t get caught in such a false dichotomy! 

Spiritual Intimacy. Now, let’s not get all religious here. I’m not referring to drinking the same Kool-Aid together and imposing one’s god on another. What I do believe is important is a yearning for deeper spiritual understanding, encouraging each other to continue to peel back layers and discover that deep center of divine consciousness. Antagonism toward one another regarding spiritual matters is not a relationship killer, but can create a certain degree of sadness. This connects somewhat to intellectual intimacy and the efforts of lifelong learning. Abiding peace in a household is quite possible when both mates are hungry for spiritual growth, but that growth will look and feel particular to each person and the overall relationship. 
Physical Intimacy. This dimension is really the culmination of the other three. Physical love is incredibly enhanced by feeling intellectually emotionally and spiritually close to someone; for we are at our most vulnerable when making our bodies available to another. I believe it is really important, if at all possible, to continue to cultivate physical attraction to one another in a love relationship. Many take this for granted or blow it off; but if there is not a physical or health limitation, then do what you can to feel sexually attractive and enjoy how that enhances your physical intimacy with your mate. 
There you have it. I pray that thinking through these four dimensions helps you to become even more intentional at enhancing or pursuing enduring love. We are hard-wired to romantically love another person, for through love one individual recognizes the shared divinity within another.