Boy-girl relationship is a very sensitive issue that needs to be addressed carefully and that all Shari'ah rules and standards should be taken into account when dealing with it, otherwise it will result in serious difficulties. The legal and moral laws of Islam in this regard are aimed at minimizing the relationship between a woman and a man because these relationships, if intimate and affectionate, will entail evil and corruption. Therefore, we advise you to suffice to minimum relationship with with members of the opposite sex even in your work or education environment. Unless necessary, you should avoiding having any contact with a person from the opposite gender.
In fact, most of these moral complications faced by the youths stem from unrestricted relations. Obviously, in the beginning such relations do not appear to be very important and one does not feel like he is going to face a danger but as time passes and the relations deepen and the two sides become further affectionate, the psychological and spiritual sensations begin to flicker with the transient feelings and physical desires coming to him. It is then that he should face the evil consequences of these relations. Perhaps, there are some people who might not face any problem because they control their desires but that is an exception.
In addition, what is the need to maintain your relations with the said boy? If you do not have a particular decision, then why is it so difficult to separate from each other? The fact that neither of you has expressed love nor affection does not mean that there is no affection between you. You should note that great sins begin from small ones that are normally considered to be insignificant. Healthier and cleaner pre-marriage relations will affect your life in future even if it may be with the said boy. We believe you should stay way from the said boy so as not to be afflicted with the negative effects of a sensational and emotional decision. Such precautions are reasonable. It has been reported that the Commander of Faithful, Ali (a.s.) did not greet young women. He said: "I fear lest something should enter my heart by hearing their greetings in return, something whose harm may be greater than the reward of a greeting." 
It has been mentioned in the history of Prophet Moses that when Shoaib's daughter was guiding Moses (a.s) to her house, she was in front and Moses was behind her. Prophet Moses noticed that the wind was blowing the girl's dress up, then he said to the girl: "Let me walk in front and you tell me which way to go when I reach the crossroads."  That was how Prophet Moses (a.s) displayed his modesty and continence. Therefore, the duty of other individuals is very clear where religious guardians exercise such precautions. Even hearing a non-mahram may leave a negative impact on a person's heart. Of course, one might find some justifications for himself e.g. the relationship is essential or it is very natural and humane and the likes. But one should note that these are mere justifications on the part of the carnal soul and Shaitan and that these justifications have no effect on truth. The more the relations between a boy and a girl and the deeper their romantic love, the more the delinquency and abnormality become in the social and family relationship. Then it becomes more difficult to attain proximity and closeness to Allah; thus the transient pleasures deprive a person from eternal and lasting pleasures.
Question 1044 (site: 1110) (Islam and Healthy Boy-Girl Relationship)
Question 6086 (site: 6278) ( Having a Relation with non-Mahram before Marriage).
 - Kulayni, Usul-e Al-Kafi, vol.2,pg. 648, hadith 1, Greeting Women
 - Makarem Shirazi, Naser, Tafsir Namuna, vol.16, pg. 59, Dar al-Kutub al-Islamiyah, Tehran Publication, first edition, 1995; Fakhr al-Din Razi, Abu Abdullah Muhammad bin Umar, Mafatih al-Ghaib, vol.24, pg. 590, Dar Ehya al-Turath al-Arabi, Beirut, 3rd Edition, 1420 A.H.