People have a natural need to preserve their emotional freedom. You need to recognize this. You can not press the issue and talk her out of giving it up. She has to come to her own conclusion that a relationship with you is preferable to an independent single existence. The prime reason will be because you satisfy her emotional needs. That is what you must work on. Of course, this works both ways. You will have to make the same sacrifice. That is what makes relationships so difficult. The conditions and circumstances must be right for both parties.
Unfortunately, the Beatles were not quite correct when they sang, "All you need is love." You must have boundaries. You probably already do without recognizing them as such. A boundary is an invisible line between you and another person. You have to maintain your identity as a unique person in any relationship. There is an old saying, "good fences make good neighbors." No matter how close and intimate you become with someone, you must preserve your self-respect. Good boundaries make good relationships. They must be in place and clear to both parties early in the dating process. It works both ways. Some men do not respect the boundaries of single women. They will be jealous, possessive and controlling. Don't violate a single woman's boundaries. Don't let her violate yours.