An excellent question, posed by a friend of mine. In fact, a young man in my life just posed the same question to me. Why do you love me when I consistently fail? What's in it for you?
Please remember that real love is the unconditional kind. Not obsessive, not infatuation, not superficial. That when we make decisions to love somebody, it should not involve any selfish intent. It does not require "something in return." This is not a business arrangement. Nor should you be thinking that I am going to control and change you to suit my needs. That includes, most importantly here, any idea that I can influence or induce somebody into loving me back.
Whether the people we love...love us back is really not that important to a point. We are invested in what we can control. We love unconditionally and selflessly. We let people be who they are. And love is generally returned to us. If it is not, if we feel as though we have become doormats or are being taken advantage of (this is victim thinking but it exists) then we must ask ourselves a simple question. How much of this will I endure? My capacity for endurance is great. But there comes a point when love crosses the line. That point when we recognize that the people in our lives are simply incapable of returning our love. I have no expectations on return capacity- I know intuitively when the effort is returned. Sometimes return capacity is greatly diminished.
This might involve poor family imprinting. A simple inability to grasp what love is. It may mean that we are simply growing weary of each other- that we are actually falling out of love. It may mean the person has a mental illness, a drug, or alcohol problem.
Love is not co-dependence. It is not self driven fear. It is not pain and suffering. In fact, sometimes love means we have no other choice than to let someone go. That our presence in their lives is preventing or stunting them from development or a greater capacity to love.
I find that in my life, if I know 100 people, that each of them has a different definition for love. But that rarely can any of them practice unconditional love. They practice conditional love almost always. Ok, I agree to love if you do this, this, and this. If you will just quit doing this, this, and this. If you don't comply with these demands, I shall withdraw my love for you. That is what we really practice. That isn't love. That's fear. Hostage taking. Putting lipstick on fear and calling it love- well we just don't have that alchemy. They are mutually exclusive. They cannot exist in the same place at the same time- like fire and water. When love turns into emotional hostage taking- then it is no longer love.
So to answer the question. It is possible for us to invest emotionally in our relationships? Nearly 100% so. It is impossible to think that we can make someone love us back in that same capacity. In fact, it doesn't really matter whether they do or they don't. We do our best. If they are able to return the favor we are enormously happy. If they cannot, we are still happy. If we have done our best, and our loved ones can't reflect our love back- we are simply left with a choice. Am I engaged in this relationship for reasons other than love? Am I fearful? Am I happy? Do I feel sorry for this person? Am I trying to perform a rescue here? There is a life cycle to love, like all things on this planet, and ultimately you are left with a choice that only you can answer. Sometimes that choice must be to detach. We have done our best. We have thrown the kitchen sink at this thing and there is simply nothing else we can do. Often when we detach, we are showing the ultimate love. Love for those that still need to progress and love for ourselves. Perhaps it is we- who will progress.