There's the obvious culprit: a dominator culture that values power-over tends to see the person who is giving as stronger and, by inference, the one who is receiving as weaker. The implication is that if you have something (time, energy, money, advice, insight, support, compassion etc.) to give, you must be doing something right, and if you need something you cannot provide for yourself, you must be doing something wrong. In part, this goes along with the cultural premium that is placed on independence- a fallacy if there ever was one in an inter-dependent world.
"We accept the love we feel we deserve," is a line from the movie The Perks of Being a Wallflower. Perhaps, if we are reluctant receivers, it is because we have been taught to believe that we are not deserving- a belief worth challenging as we learn to cherish ourselves.
The sad thing about not trusting our boundaries and our right to say "Yes please," or "No thank you," is that we may develop the habit of being non-receptive, of not really taking in what is offered and allowing it to replenish us each day. This can leave anyone who is giving feeling unreceived and the receiver strangely hungry for what is offered but not really received.
Today, may we take in with gratitude and without fear that which we choose to receive, and may we give without resentment that which we can offered in a truly sustainable way.