love?

When I skim through my notebook, I find a profound sentence that was said by my instructor in Shandong University at our first class meeting. He said that: “I will not forbid the love affair between boy and girl. But, I sincerely hope you do not yield to carnal desire, lonesome, or the greedy for warmth.”
I find that the love affair prevails among is. Some people are in sweet love. Some people keep the love for a very short time. Some people extremely miss their lovers in China. Since we come to this strange environment, we may feel lonesome and long for a person to accompany us. Nevertheless, I feel it is indiscreet to confirm this is love. It is moved as a fellow sufferer. Moreover, little love between undergraduates can be lasted throughout the life. So I prefer to act as a good friend rather than love and then break up. I am afraid to lose an intimate friend.
Somebody has said that: “when you feel helpless and confused, the god will dispatch the angel to accompany and comfort you. After your life steps into regular, they may leave.” I admit that I have met some boys who encouraged me to overcome the difficulties when I was under enormous stress. Sometimes I held a special feeling to them but I did not think it is love. Nowadays we are just close friends, get contact with each other occasionally and then lead a respective life.
I do not know what love is. In the serial, Guo furong says that: “if you fall in love with somebody, at the beginning, you enjoy the unbridled passion. However, he is the person who you need to live together throughout your life. Ten years or twenty years later, when the passion fades away, how can you continue to live together?” she gives the answer “what you have suffered together can remind you of the present happiness. As long as you evoke the memory that you went through many difficulties in order to get together, you will treasure you present life. It may be insipid but it must be valuable.”
Perhaps she is correct, but I recall a gloomy love folklore------the love between Bai Suzhen and Xu Xian. Bai Suzhen is winsome, virtuous and gentle. All fine qualities assemble in her personality. She has saved the life of Xu Xian. But finally she loses her glamour for Xu Xian. He has a dubious relationship with her sister. He is tired of her. The unalterable oath of love seems to be a joke. I cannot understand.
What is love?