Answer
If you love a person and wish to marry him/her, you should adopt the means to fulfil your wish.
Your wish cannot be fulfilled by merely prescribing some Du’aa without adopting the means. Marriage is a mutual issue between two partners. There must be a proposal and consent. If you find the person to be a suitable partner, you should send a proposal and wait for the response. It will not help you not informing the person of your intentions to marry him/her. In fact, Shaytaan will use the thought of the person you love to mislead you with evil ideas and thoughts. That can be very detrimental to your spirituality.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai