The world has it all backwards when it comes to building romantic relationships. The world says, find someone who is fun to be with and that you're attracted to, then build a relationship (often built primarily on sex first) and if you don't break it off and can still stand each other after awhile, maybe start thinking about marriage. Then, once marriage happens, the rest of the world's advice has to do with how to deal with the various issues that inevitably crop up when you've built a relationship on fun and physical attraction and later find out your goals and values are different. The world will also tell you to leave the relationship, even a marriage, as soon as you find attraction waning or problems that aren't easily solved.
Too often, the church tries to do things the way the world does, except without the sex before marriage. Too many Christian young people were never given guidance on what to look for in a spouse and make the decision based on feeling in love after spending time having fun together. But even where guidance is given, it's often still focused on finding someone you're attracted to who happens to have the right qualities rather than learning first to be attracted to the right kind of person. In other words, even Christians usually believe that attraction is fixed and involuntary and try to center relationships around it anyway.
I suggest a better way. My advice is that we learn to be attracted to good character and the types of traits that make a good spouse. Attraction isn't something that just happens to us. Attraction can be controlled to a large extent. We all have preferences for physical characteristics in the opposite sex, but attraction is more than just noticing someone is good looking, even if that does play a part. These other factors that influence attraction are primarily driven by our mindset and can be modified by our patterns of thought.
In order to control our attraction properly, we should actively think about good character qualities and notice them in others around us and think positive thoughts about those who have them in order to develop a mental pattern of appreciating good character. The opposite should be true of bad character qualities - we should practice seeing them as unattractive. In addition to this, it's important to actively work to downplay the role of physical traits in our attraction so that character becomes the main factor, not more superficial characteristics like height, hair color, or facial features.
For example, a single woman should learn to appreciate men with a good work ethic, leadership qualities, self-control, and an interest in studying the things of God. She should control her thoughts so as to make character the main thing she evaluates about others and so that she values good character. Thus, she should find her interest in an available man growing when she observes good character while she should find her interest in him waning if she finds bad character such an inability to keep a job, passiveness, sexual immorality, or an anger problem (to name just a few issues).
If we teach our young people to value the kinds of traits that make a good spouse and to actively work to be attracted by their presence and repelled by their absence, they will make better choices when it comes to marriage.
For married people, I would suggest a modification of this idea. Rather than working to value just good traits in general, I recommend that we learn to appreciate and become attracted to the good traits our spouses have. Rather than focusing on the flaws, of which all people have some, look for and focus on the good traits and learn to let your heart beat faster over those. Install a permanent pair of rose-colored glasses after the wedding and let patterns of appreciation for your spouse become a habit.
In short, don't be a passive observer of your attraction. Take an active role in building the right mentality so that you prepare yourself for a lasting and loving marriage.