All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
There is no doubt that marriage is among the good matters which a Muslim should take the initiative to perform without delay. There are great objectives and many benefits of marriage, the most important of which is to keep both spouses chaste especially at the present time when the reasons of temptations are so many.
Therefore, we advise you to try to convince the parents of this girl to agree to conduct her marriage contract. First of all, you should seek the help of Allaah and then the help of whomever you think may influence them. If they are convinced, praise be to Allaah, and if they insist on refusing, then it is not permissible for you to conduct the marriage contract with her without the consent of her guardian because the consent (and presence) of the guardian is a condition for the validity of conducting the marriage contract according to the most preponderant opinion of the scholars . For more benefit, please refer to Fatwa 83629.
On the other hand, if this girl fears that her guardian may prevent her from marriage without a sound reason, then she may take the matter to the Muslim judge; and if it is confirmed that her guardian prevents her from marriage without having a sound reason, then the judge may marry her off or appoint someone to marry her off.
However, if marriage with her is not facilitated for you, then you should look for another girl to marry, and Allaah may facilitate for you someone better than her, as there are so many other women. Allaah Says (what means): {… and it may be that you dislike a thing which is good for you and that you like a thing which is bad for you. Allaah knows but you do not know.}[Quran 2:216]
As regards loving her and being attached to her, then this is something that can be treated; for more benefit on the treatment of love sickness, please refer to Fatwa 84544.
Allaah Knows best.