Hmm, that cycle of acceptance/rejection can do 2 things to you. Help you grow into a loving being, or make you shrink back into your shell and never allow anyone to hurt you again (that never works). Sometimes we reverberate between these two extremes, trying to find a way out.
It is better to grow into a loving individual who knows how to give unconditional love. Don't expect anything in return :) just shine in your capacity to love, even when it hurts the most.
But if the other person does take you for granted, it's time to move on. That person is selfish, and far behind you in terms of growth. The worst part is, he/she might stifle your growth as well. With your capacity for unconditional love, you should find someone worthy of receiving it, and getting back some without asking for it :)
Good luck!