I haven't yet felt the love of a mother to a child or the love that two people feel when they commit their lives to one another. However, I think it's safe to say that I love deeply. Even without having the aforementioned love situations, I have people in my life that I just love without limit.
It can be a great thing, but it can also drain you. What I'm starting to learn is that you just have to love and not worry about how the other person responds. I'm not talking about going crazy or smothering or anything like that.... I just mean, you have to love them and just be. You can't help how much you love them and you can't help how much they do/don't return the feelings.
No matter what, you don't let them punish you for it and you don't punish yourself.