Because first you must ask what love is and the Bible puts it this way 1Co 13:4 Charity suffereth long, and is kind; charity envieth not; charity vaunteth not itself, is not puffed up,
1Co 13:5 Doth not behave itself unseemly, seeketh not her own, is not easily provoked, thinketh no evil;
1Co 13:6 Rejoiceth not in iniquity, but rejoiceth in the truth;
1Co 13:7 Beareth all things, believeth all things, hopeth all things, endureth all things.
1Co 13:8 Charity never faileth:
Personally last year I spent months studying just this passage and studied it with the slant on what the Bible has to say about dating, and I have about 16 pages on microsoft word about what that means in just the context of finding a spouse.
The one thing I will say is that the phrase Charity sufferth long, and is kind; is the only one that ends in a semicolon in this passage so that indicates that those two phrases are dependent on one another. So we are to be kind even when we suffer. Difficult.
If you want a very long answer to that question and you have a dollar read this http://www.amazon.com/Tortured-Christ-Richard-Wurmbrand/dp/0...