A loved boy (or LB) is a boy who is or has been in a loving and warm relationship with a boylover. Some use the term only about people who are now adults. Others use it to describe people who are currently boys and are in serious, committed relationships with men. Often the term will be used to describe a boy who is aware of the culture of boylove and understands the element of sexual attraction involved.
Like the term young friend, the term "loved boy" does not necessarily imply a sexual relationship, although many consider the latter term to indicate a much more serious, mutual and loving relationship than the more casual "young friend."