Share your feelings.
If you are not ready to give up on your relationship completely, give it one last chance by telling your partner how you feel. Let your partner know that you feel that the relationship is one-sided. This gives your partner a chance to make it right if he is, in fact, actually committed to your relationship and just not very good at showing it.
Resign yourself to the end of the relationship.
The end of a relationship is almost always a sad affair. While there is no way around the temporary emotional distress that accompanies a relationship's end, it is important to remind yourself that you are not getting what you need out of the relationship and that ending the relationship is really your only recourse.
Break things off.
Tell your partner that you feel that your relationship has run its course. Don't leave your partner guessing as to the reason why your relationship has reached its end, but instead tell her that you just don't feel like she loves you the way you love her. Ask her to respect the fact that you need love in return and to let you go since she can't give you the love you seek.
Move forward, seeking a more equally loving relationship.
As you start new relationships following this abandoned one, focus on finding ones where your love is reciprocated. To avoid having to go through another potentially painful breakup, consider at the start of each new relationship whether or not you feel that your love is being returned. If you think your new relationship may be as one-sided as the one you left, discuss the problem and end it if it can't be resolved.