To like or love someone means that we enjoy that particular individual for certain unique qualities that fit with our interests and needs. It means, too, that we have, not just an opinion, but a feeling about that person.
Oftentimes, we hear people say, "it's not easy for me to make friends." Even though we may enjoy and need to be alone now and then, we are basically social animals who need the company and cooperation of others. We need to make friends, to like and be liked, and to form loving relationships with at least a few people who are in some ways special to us.
To understand the relationships that people form, it is important to realize that we are not focusing on individual behavior. Instead, we keep meaning to understand behavior between pairs of human beings and the reasons people like and love those they do.