Please give me input on what to do to love my fiancÚ more without being impure or immoral with her.
Perhaps the greatest passage dealing with courtship and marriage is the Song of Songs (also called Song of Solomon). I will not get into that, however, but give you some other scriptures .
Romans 12:10, "Be kindly affectioned one to another with brotherly love; in honour preferring one another," may be talking about all of our relationships, but it especially applies in our relationships with those we love such as a future spouse. In all things treat the other person better than you would like to be treated yourself. Don't do anything to injure the person or her honor.
Hebrews 13:4-6 says "Marriage is honourable in all, and the bed undefiled: but whoremongers and adulterers God will judge. Let your conversation be without covetousness; and be content with such things as ye have: for he hath said, I will never leave thee, nor forsake thee. So that we may boldly say, The Lord is my helper, and I will not fear what man shall do unto me." While most would say the latter two verses are separate from the first, they still apply. Those going into a marriage should keep the marriage pure, and the desire of one to defile it beforehand is covetousness, adding sin to sin. Some might argue that the passage doesn't outright condemn sexual relations before marriage, but when coupled with the verses on covetousness I think it may.
The first nine verses of 1 Corinthians 7 point out that sexual intimacy is meant for marriage and to engage in it outside of marriage is wrong. In this day when a couple is not considered married until it is recognized by the church or civil government it is better to wait to avoid any appearance of improper behavior.
I have sometimes thought that the proper way to treat your fiancÚ is to treat her like any other woman, only more so. Compliment her more, giver her gifts, treat her special. But anything you would find improper with another woman would be even more improper with her.
Perhaps the first thing I should have said is to pray. Pray in private that you can avoid impurity and immorality with her. Tell her you are praying this, and pray with her for the same thing. Since you are going to be married, you might as well start now praying with her, because if she is not willing to pray with you she will object to other things you hold dear because you hold God dear. It will also show her you want to do the right thing, and she will help you to do so.