Love is when the other person has value for its own sake
Few actions occur purely for its own sake. Love is the attribution of value for no other reason than for its own sake.
When we fall in love, we are essentially appraising the value of the other person. We weigh them up against other things or people and decide if they are of sufficient value or not.
As people, we decide another human’s value by how well they respond against the values we hold. For example, if we have been raised to be honest, we may perceive honesty as a trait in others that increases their value. The depth of our love corresponds to how highly we value that person. Once we deem someone to be of sufficient value, we make ourselves more vulnerable to them. The way they respond to this vulnerability will also add or detract from their value appraisal. This can explain why we have more positive attitudes towards someone that loves us. When someone loves us, we often have increased feelings of affection and warmth towards them, which can even lead to us loving them. This is because when someone loves us, their value increases to us. If, in the future, your partner changes, the value you hold of your partner will also change. The value can increase, or it can decrease. Viewing love in this way can account for love diminishing. If a partner changes in certain ways that make them less valuable, love diminishes. When we choose a partner, we are also assessing their capabilities of changing into someone with less value. If they have the capability to change into something we may not like, this is reflected in our initial appraisal. 
If falling in love is nothing more than an appraisal of another person, why do we not feel the same feelings when we are interviewing a candidate for a job? In both cases, we are conducting an appraisal of the other individual, yet one process comes with a very distinct feeling, while the other does not. Addressing these feelings is a crucial part of defining love. Without feelings, love cannot exist (as in the case of the interviewer). Any definition of love that does not address the emotions involved cannot adequately explain the phenomenon of loving another human. Also, this description of love and the way we fall in love cannot adequately explain familial love. The unconditional love of a parent is just that, unconditional. It does not stem from an appraisal of character. This is why parents often remark how they still love their children even in instances where the child has committed mass murder. This demonstrates better than anything that love cannot be reduced to an appraisal but relies on an emotional connection. 
[P1] We decide who is worthy of our love by appraising their value. [P2] Therefore, love can be reduced to the value we perceive in another human.
[Rejecting P1] An appraisal is not the only component of deciding who to love. There are also emotional elements that need addressing.