If you really feel the way you describe about her, then you are not doing her any favors by getting married. Be REALLY truthful about your feelings before getting married.

Your statement of not failing her is B#%%. You are failing her if you marry her under the conditiond that exist. She may hurt for a while if you let her go, but don't make her suffer for the rest of her life. You are not being fair to her by trapping her in a marriage that isn't what a marriage should be.

Grow up. Your feelings and hers are all that are a part of marriage so if you do not have feelings DO NOT go ahead with the marriage. You will never have a commitment to her for life if you don't have the feelings that are necessary for a successful marriage. A wife does not need a husband who will "care for her as much as possible". For heavens sake, let her go so she can have a successful life of her own without someone who does not care for her as much as she deserves in a marriage.

You don't own her just because you asked her to marry you, so let her go.