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, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
First, we congratulate you on the blessing of embracing Islam. This blessing requires thanking Allaah The Almighty by seeking beneficial knowledge and being keen on doing good deeds as well as accompanying the righteous Muslim women. We ask Allaah The Almighty to Grant you a righteous husband who will make you happy in this world and in the Hereafter.
You were right when you were keen on marrying this young man for his righteousness; however, you were wrong because you considered that your happiness is based on marrying him. Many women thought the same, but after their marriage to the ones they loved, their marriage failed. Allaah The Almighty Said (what means): {But perhaps you hate a thing and it is good for you; and perhaps you love a thing and it is bad for you. And Allaah Knows, while you know not.}[Quran 2:216]
Therefore, we advise you to leave this matter to Allaah The Almighty and perform Istikhaarah (guidance-seeking prayer) regarding marriage to this young man, and Allaah The Almighty will determine what is good for you by His permission. For further information about Istikhaarah, read Fatwa 81434.
With regard to this young man’s obedience to his mother and refraining from marrying you, this is lawful because obeying his mother is obligatory for him, but marrying you in particular is not. However, he should try to convince his mother in every possible way. If she agreed, then praise be to Allaah The Almighty; otherwise, he must obey his mother unless he feared to be tempted because of your relationship. In such a case, it is permissible for him to marry you even if his mother did not agree, then he must do his best to please her.
Anyway, if you could not marry him, search for another man hoping that Allaah The Almighty will grant you a better man. Indeed, there are many other good men and you should know that there is no harm if a woman offered herself in marriage to a man as long as she observes the Sharee‘ah regulations including politeness and modesty. You may also seek the help of your Muslim sisters. To know more about the remedy of love sickness, see Fatwa 84544.
Moreover, you should know that the Muslim should not abandon marriage totally, marriage could even be obligatory for the one who fears falling into temptation.
On the other hand, if you could not marry this young man, you have to expiate the oaths you made only once because making repeated oaths regarding the same thing necessitates one expiation as long as these oaths were not broken more than once.
As for the Hadeeth to which you referred in the question, it proves that if a woman was forced to marry someone against her will, she has the right to cancel this marriage. There is a difference in opinion among the Muslim jurists regarding the ruling on forcing the adult virgin to marry against her will, but the sound opinion is that it is prohibited to force her to marry against her will.