i see it as a belief that it is possible to make a decision to care about someone in a deep and meaningful way that would make them a permanent part of my life in one way or another.
+1
It's not a simple concept, nor is it an illusion. There is illusion in infatuation or lust, but not love. "Love is blind" is not true. Infatuation is blind. Love is eyes wide open. Loving someone meaning knowing them and loving them as is. This doesn't mean a relationship will work, but that there is potential. If anyone believes loving someone means you can change them, then they're going to be very disappointed.
The experience of it that makes it what it is. It's not the same for everyone. I think too many people call what they feel love when it's something else. Intense passion and novelty of meeting someone amazing can feel like love. Lust and infatuation feel like love. Admiration or adoration can feel like love. However, love is not a momentary intense feeling that is always heightened. It requires you to see the person as they are, not what you think they should be or what you want them to be. For a relationship between two people who love each other to work, this requires understanding, committment, loyalty, respect, and consideration. These are the intentional aspects of love.
I believe there is a midway point between liking and love. Many are in that area, but it's easier to simply call it love because we like to have things defined. This tendency to call every intense feeling or emotion love, diminishes the significance of true and substantive love.
Love is not a relationship. These are two different things. You can love someone yet not have a great relationship with them, whether because of poor relationship skills, divergent beliefs or feelings about the relationship, or conflicts or disagreements about what each person wants or expects.
Love is a feeling separate from the action. Someone can love you but not show you they love you in a way you feel loved. This is why we have five love languages.
When you love someone, you take on their feelings as well as yours. You don't put yourself first. It's not an equal opportunity concept. When you love, you don't think in terms of 50/50. Each person (without realizing it) usually thinks or acts in terms of 75/25. Some people don't require anything of the other person except a hope that they feel the same. Loving someone usually entails wanting to do things for them, just because you want to, not because you expect anything in return. You will feel for them and give to them in ways you did not expect or imagine. It's not conscious or intentional. It just is. Love has no expectations except to feel and embrace all that comes with feelings for that person. A relationship, on the other hand, involves expectations. For example, two people may love each other but can't compromise about anything. This doesn't mean they don't love each other. Rather, it means, they can't compromise as a couple. Yet, they can still love each other to death (figuratively).
Of course, if there is no reciprocation, love will be harder, and this lack of return of love can end the feelings of love and the relationship. However, love (as feeling/desire/emotion), and love (as action/behavior) should be understood as separate concepts. They are not the same.
Love can progress quickly or slowly. There is no one way to understand it. Some people find it easy to love, and others find it difficult. To define the experience for everyone as a universal concept will limit how it can be understood.