When I was digging into what other people's life is about, I found that there is a type of people whose meaning of life is oriented about helping others (altruism). I was a bit surprised how that can be a source of fulfillment as in a sense you are just giving and not having something in return. I thought what brings satisfaction is the act of meeting ownself needs, such as, being loved, respected, and in control.
That was until I've realized that we as humans build bonds between us in a way that can reach a level where what hurts others can hurt us as well. No wonder why parents put their lives at the edge to see their children flourish. Also, no wonder why couples sacrifice for each other in the name of love. It just hurts them when they see their lovers hurt and this is what I think is the optimal connection.