No, the best thing is loving someone else. Getting anything in return is irrelevant. It's not a factor. We do it because seeing them happy makes us happy, and for no other reason. When we love someone, we will sometimes go to extreme lengths just to be with them.
Love feeds on itself.
When someone loves us, it makes us love not only them, but other people too. We go around spreading love, because we know from personal experience how great love feels. No matter how many times a relationship turns sour, most of us will never entirely give up on finding love. Because ultimately, we have faith that when we finally do find it, it will be so wonderful that all the garbage we had to sort through will seem worthwhile. Now that I think of it, maybe a holiday devoted to the celebration of love wouldn't work.