She is in love with a Muslim and wants to marry
    him – does she have to become Muslim?
Question

                I am a Christian and is in-love with a
      19-year old Muslim boy.
 He is very nice for accepting me not as a virgin.He proposed marriage to
      me and I am making plans about it. Is it necessary for me to convert to Islam if I marry
      him even I don't like to do so. We talked about the children that they will be Muslims.
Praise be to Allah.Yes, it is very necessary for you to enter Islam. This will solve 
  all the problems, from making the marriage valid, through giving a united direction 
  to the future upbringing of the children, to attaining success and happiness 
  in the Hereafter. Your feelings of unease about taking this step may be due 
  to the difficulty of leaving behind what you are used to and the religion that 
  you have grown up in, or reluctance to go against your family and relatives, 
  or fear of hostility and criticism from others, or concern about losing some 
  worldly advantages. But all these issues will be easily overcome when you seek 
  the help of Allaah and are determined to follow the truth. The wise person is 
  prepared to make sacrifices and put up with difficulties for the sake of following 
  the truth, because the truth is worth pursuing. Any difficulties encountered 
  will become easy because the result is happiness in this world and the next, 
  and Paradise the width of heaven and earth. Moreover, your marriage will help 
  you to live in love and harmony with your husband (if he repents to Allaah for 
  the forbidden relationship and becomes a religious person of good morals) and 
  his Muslim family. There will be no dispute as to which religion the children 
  will be raised in, and they will not feel that there is any conflict in the 
  family, so they will be able to grow up free of the psychological complexes 
  that result from the parents difference of religion. Other people have 
  felt something similar to the feelings that you are experiencing now, as is 
  reflected in the following story, which happened at the time of the Prophet 
  of Islam  (peace and blessings of Allaah be upon 
  him). Anas reported that the Messenger of Allaah  
  (peace and blessings of Allaah be upon him) said to a man, Become Muslim. 
  He said, I feel that I dont want to. He said, Become 
  Muslim, even if you feel that you dont really want to. (Reported 
  by Imaam Ahmad, 11618; Saheeh al-Jaami, 974). This is the correct approach 
  which people should have towards the true religion. For more information on 
  the topic of marriage, please see Questions #3025 
  and #2527. We wish you every good thing 
  and success. Peace be upon those who follow true guidance.