Love is a very interesting concept. On one hand, it's very selfish, because you only love whom or what you "choose" to love, and there's no going around that, there's no faking it. On the other hand, once you choose the object of love (be it a person, a cat, a plant - I'm not necessarily talking about romantic love here), you do the exact opposite of being selfish and egocentric - you include those objects in some layer of you, and you show them how much you love them. That's strange and wonderful.
The only ones who require actual proof that you love them back are people, and the more meaningful you are to them (and usually vice versa), they tend to demand more proof. Why? Simply because they are insecure. We are all insecure in many ways, and I say that despite being one of the lucky ones who don't have to "earn" my husband's love or constantly prove mine to him. We all have our insecurities, usually the ones we grow up with (things we witnessed in our parents' homes, in our community, etc.). It's very sad that we, as "superior beings" on this planet, seem to have more trouble than any other kind of being when it comes to handling love, of all things.
But really, one of the first and most important keys to knowing that you are indeed loved, is loving (or at least mildly liking) yourself. Because that gives you the ability to believe that if you can do it, perhaps others would be able to, as well.
Have a lovely weekend :-)