The word "love" is used in so many ways, that it is difficult to come up with a single definition that does all of them justice. Of course a good part of the problem is either caused by or aggravated by the fact that people use the term incorrectly.
But I think I shall try to formulate a definition that works.
"Love is that loyalty that arises out of a social affection that sets itself upon another human being and unites with that being in a regulated social context." Many things that are actually quite selfish in nature may claim to be love, but it properly belongs to love to be both unselfish and happy while seeking the welfare of another.
There are many degrees of love, of course. So, also, there may be different phases and kinds in a relationship that is loving from beginning to end.
There is such a thing as philanthropy (love of mankind) that animates a good man to labor for the good of others. Thus we have our example in Jesus Christ, whose love for mankind led him to lay down his life. But there seems also to be a warmer love than this for those who are closer. Love for neighbors, friends, near kindred, husband or wife, and children all seem to come in some way or another properly under this idea of loyalty and unselfish concern
Selfishness, as opposed to love, has its eye on the object of its affection in much the same way that a bird of prey may have an eye on its victim. When we proclaim our love for a beautiful spring day or for bratwurst, we speak of the approval we have of the day or the meat as a way of pleasing ourselves.
Dressed in the clothing of "true love," this selfishness may even seek out its object and practice some degree of benevolence toward the object of its affection. However, after winning the heart of another, this person will soon show by selfish exaction and unjust jealousies that it was not love at all that made him desire the company of another.
The same can be said of the recipient of such attention. If the recipient lacks the wisdom necessary to see that selfishness can wrapped in the name of love, perhaps she too longs more for attention than for returning the love of another. Gratified vanity may be another response that the responder wrongly thinks to be responsive love.