According to psychologists, giving something of value has a positive effect on the person that is doing the giving. Those who care, give, or help in an unsolicited manner tend to feel more positive, alive and have higher self-esteem. The effects of emotional or any other type of support on the partner that is on the receiving part of this equation, however, is much more mixed. On one hand, this can generate feelings of gratitude, and improve compliance with later requests.
On the other hand, this behavior may lead to negative feelings of obligation. This is why you need to take your partners needs into consideration before you do any action. At first, it may sound complicated, but keep in mind that the longer you are together with your partner the more likely it is that the two of you know each other enough to be able to accurately predict each other's needs and wants.