Whenever you hear people tell you that love is something either done freely, or not at all, listen to them, for they know what they're talking about. It means they've been round the block with it more than a few times.
Whatever else love is or may be, it is not simply (and brutally) a matter of doing more for somebody, and then more and more and more. I can go, as they say, to the ends of the earth for another human being, and then back again, but if I'm doing it chiefly in order to maintain their good opinion of me, or to maintain myself in their good graces, then it's hardly a free act. At least not in the oldest and noblest sense of that word. Which is to say, something done free of charge.
Of course people can play all sorts of games with my conscience: they can try to turn what I could have sworn was a gift into a debt, something I thought I desired to do from the bottom of my heart into something else that was really owed all along. But my love shall dry up at a dismaying rate, if I find myself doing one favor for someone, and then another and another and another, simply in order to assure them I'm not quite as bad as they're always on the verge of thinking I am. And as I know they will think I am, sooner or later. Unless, of course, I keep on doing that thing they expect which I thought was a free act of service, but which "in reality" was merely partial payment for services they rendered "to me."
I'll say it again: Love is either a free thing or it is a miserable thing, which very soon will cease to bear even a shred of resemblance to love. So that, soon enough, I'll have all I can do to keep from hating those who keep escalating their expectations of me. Even as I continue to try to meet those same expectations. Just to maintain my self-respect, of course. Or to ease my conscience.
And needless to say (or it ought to be), the fact that I must be prepared for other people's games with my conscience doesn't mean I'm not playing them myself.