A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another.By this shall all men know that ye are my disciples, if ye have love one to another. John 13:34-35

If ye love me, keep my commandments.  John 14:15

Greater love hath no man than this, that a man lay down his life for his friends. John 15:1

This is my commandment, That ye love one another, as I have loved you. John 15:12

These things I command you, that ye love one another. John 15:17

Let love be without dissimulation. Abhor that which is evil; cleave to that which is good. Romans 12:9

Be kindly affectioned one to another with brotherly love; in honour preferring one another; Romans 12:10

Owe no man any thing, but to love one another: for he that loveth another hath fulfilled the law. Romans 13:8

Love worketh no ill to his neighbor: therefore love is the fulfilling of the law. Romans 13:11

But as touching brotherly love ye need not that I write unto you: for ye yourselves are taught of God to love one another. 1 Thessalonians 4:9

But the fruit of the Spirit is love, joy, peace, long suffering, gentleness, goodness, faith, Meekness, temperance: against such there is no law. Galatians 5:22-23

Let brotherly love continue. Be not forgetful to entertain strangers: for thereby some have entertained angels unawares. Hebrews 13:1-2

Be ye therefore followers of God, as dear children; And walk in love, as Christ also hath loved us, and hath given himself for us an offering and a sacrifice to God for a sweet smelling savor. Ephesians 5:1-2

And though I have the gift of prophecy, and understand all mysteries, and all knowledge; and though I have all faith, so that I could remove mountains, and have not charity, I am nothing. 1 Corinthians 13:2

The type of love these quotes are about is mostly brotherly love, not romantic love, but still good quotes for the week of Valentine's Day.  In Greek, the word "agape" is the one mostly translated into English as "love".

Agapao (verb) and agape (noun). This is the "Christian love" of the Bible. It means affection, benevolence, good-will, high esteem and concern for the welfare of the one loved. It is deliberate, purposeful love rather than emotional or impulsive love.

Phileo (verb). This means to love in an impulsive and emotional way. It is seldom used in the Bible.