Can he pray for a kaafir woman to be guided to Islam so that he can marry her?
Question

                Suppose you see a beautiful woman on the road and you and to marry her. But she is a kaafir. Therefore marriage is not allowed. My question is: Is it allowed to ask Allah to guide her to Islam and then marry her later?.
Praise be to Allah.Before answering the 
    question, we should say that the Muslim is enjoined to lower his gaze and 
    avoid looking at that which Allaah has forbidden. Allaah says 
    (interpretation of the meaning): 
“Tell the believing men 
    to lower their gaze (from looking at forbidden things), and protect their 
    private parts (from illegal sexual acts). That is purer for them. Verily, 
    Allaah is All‑Aware of what they do”
[al-Noor 24:30]. 
There is great divine 
    wisdom behind this injunction, for Allaah is Most Merciful and Kind towards 
    His slaves, so His laws relieve them of hardship and difficulty and the 
    causes of mental and physical torment. It is well known that the eye is the 
    messenger of the heart , so if he allows himself to look at beautiful 
    images, his heart will become attached to these images, and these images 
    will reside in his heart, then in most cases he will not be able to get what 
    he wants so he will feel anguish.  
Therefore Islam blocks the 
    way to this suffering, by enjoining us to lower the gaze. So the Muslim has 
    to follow this command in order to please his Lord and for his own peace of 
    mind. 
What you have referred to 
    in your question is correct – that if a person likes something and desires 
    it, then he has to prevent himself from attaining it in any way but that 
    which Allaah has permitted, and he should make his desires in accordance 
    with what the Messenger of Allaah (S) brought. This is the characteristic of 
    the believer. 
With regard to your 
    question, the answer is that it is permissible to pray for a kaafir to be 
    guided as is indicated in the saheeh ahaadeeth. It is proven that the 
    Prophet  (peace and blessings of Allaah be upon him) prayed for the 
    tribe of Daws to be guided, and he said: “O Allaah, guide Daws.” Narrated by 
    al-Bukhaari (2937) and Muslim 92524). 
Al-Tirmidhi (5/82) narrated 
    that Abu Moosa (may Allaah be pleased with him) said: The Jews used to 
    sneeze in the presence of the Messenger of Allaah  (peace and blessings 
    of Allaah be upon him), hoping that he would say “May Allaah have mercy on 
    you” to them. But he said: “May Allaah guide you and set your affairs 
    straight.” Classed as saheeh by al-Albaani in Saheeh al-Tirmidhi. 
Al-Haafiz Ibn Hajar 
    al-‘Asqallaani (may Allaah have mercy on him) said in Fath al-Baari 
    (10/604): The hadeeth of Abu Moosa indicates that they are included in the 
    general command to pray for one who sneezes, but there is a special prayer 
    for them, which is praying that they be guided and their affairs set 
    straight, and there is nothing wrong with praying for them in that manner. 
    End quote.  
The great scholar Ibn 
    Muflih al-Hanbali (may Allaah have mercy on him) said in al-Adaab 
    al-Shar’iyyah (1/368), speaking about what is and is not permissible to 
    say when praying for a kaafir: As for praying for him to be guided and so 
    on, this is clearly permissible. End quote. 
The one who prays for him 
    should have a good intention when saying this du’aa’, which is to attain the 
    pleasure of Allaah by bringing this woman to Islam and saving her from the 
    punishment of Allaah, and other such good intentions. There is nothing wrong 
    with also intending to marry her.  
And Allaah knows best.