Praise be to Allah.
First of all, we ask Allaah to encompass that girl with His mercy, and to admit her to His Paradise, and to bless her family and all her relatives with patience and consolation.
We advise you to treat her parents kindly, and help them to overcome their trial. With regard to yourself, we advise you to accept the decree of Allaah and to have faith that all things are in His hand (?), and that He controls all things in this universe, and He has great wisdom and He cannot questioned as to what He does, while they will be questioned.
With regard to your question about praying that this girl will be your wife in Paradise, there is no reason why you should not do that, if Allaah wills, and you may pray for that.
But what we would prefer for you is to pray to Allaah for mercy and forgiveness, and to raise her in status in Paradise. This is what will benefit her from you, and you will be rewarded for it, if Allaah Wills.
We are afraid that you may exaggerate about this matter, or use this du’aa’ too much, and that it may increase your attachment to her and affects your life or distract you from seeking that which will keep you chaste in this world, namely halaal marriage. We should also point out to you, so that you will not go to extremes in your attachment to her, that she has died and is a non-mahram to you, so be aware of going to extremes in expressing grief and sorrow for what you have missed out on, for Allaah has set an appointed time for all things.
We remind you of the verses in which Allaah says (interpretation of the meaning):
“And certainly, We shall test you with something of fear, hunger, loss of wealth, lives and fruits, but give glad tidings to As‑ Saabiroon (the patient).
156. Who, when afflicted with calamity, say: ‘Truly, to Allaah we belong and truly, to Him we shall return.’
157. They are those on whom are the Salawaat (i.e. who are blessed and will be forgiven) from their Lord, and (they are those who) receive His Mercy, and it is they who are the guided ones”
Shaykh al-Sa’di (may Allaah have mercy on him) said:
Allaah tells us that He will inevitably test His slaves with trials, so as to differentiate those who are sincere from those who are lying, those who panic from those who have patience. This is His way with His slaves, because if ease were to continue with those who believe and no trials were to befall them, there would be no distinction between those who have faith and those who do not, which leads to corruption. The wisdom of Allaah dictates that the people of good should be differentiated from the people of evil.
This is the purpose of trials, not to take away what the believers have of faith or to turn them away from their religion. Allaah never causes the faith of the believers to be lost, and He tells us in this verse that He will test His slaves “with something of fear” from enemies, “ and hunger” i.e. He will test them with a little of both, because if He were to test them with extreme fear or with extreme hunger, they would be doomed, but the point of trials is to show this distinction, not to doom people.
“loss of wealth” this includes all kinds of loss of wealth such as disasters coming from the heavens, drowning, loss, seizing of wealth by wrongdoers such as unjust kings, banditry and so on.
“lives” i.e. loss of loved ones such as children, relatives and friends from various kinds of disease in a person's body or in the body of those whom he loves. “and fruits” means grains, the fruit of date palms and all other trees and vegetables, due to hail or cold or fire or a catastrophe such as locusts and the like.
These things will inevitably happen because the All-knowing All-aware has told us of them, so they happened as He told us. When they happen, people fall into one of two categories, those who panic and those who are patient. The one who panics suffers two calamities: the loss of a loved one, which is a calamity, and the loss of what is greater than it, which is the reward he could have attained if he had followed the command of Allaah to exercise patience, so he incurs loss and deprivation and a decline in the faith that he has; he misses out on patience, acceptance and gratitude and there befalls him the divine wrath which is indicative of great loss.
As for the one whom Allaah helps to be patient when these calamities come, he controls himself and does not express discontent in word or deed; he seeks reward for that which is with Allaah and realises that the reward he will attain by being patient is greater than the calamity that has befallen him. Indeed the calamity is in fact a blessing because it becomes a way to attain something that is better and more beneficial. He has obeyed the command of Allaah and attained reward. Hence Allaah says: “but give glad tidings to As‑ Saabiroon (the patient)”, i.e. give them the glad tidings that they will be given their reward without reckoning.
The patient are those who have earned these great glad tidings and bountiful gift from Allaah. Then He describes them as “ [those] who, when afflicted with calamity”, which refers to everything that pains the heart or body or both, of those things mentioned above.
“[they] say: ‘Truly, to Allaah we belong” i.e. we are slaves of Allaah, subject to His command and control; we have no control whatsoever over ourselves or our wealth. If He tests us with any of those things, the Most Merciful of those who show mercy sas disposed of His slaves and their possessions, and there can be no objection to Him; rather it is a part of a person's full and complete submission and servitude to Allaah (‘uboodiyyah) to know that calamity has come from the All-Wise, Who is more merciful to His slave than he is himself, and that requires him to be pleased with Allaah and to give thanks to Him for His decree, because that is better for His slave, even if he does not realize that, as we all belong to Allaah, then to Him we will return on the Day of Resurrection, then each person will be requited for his actions. So if we are patient and seek reward with Him, we will find an abundant reward with Him; but if we panic and get angry, there our lot will be no more than divine wrath and loss of reward. So each person belongs to Allaah and will return to Him, and this is one of the strongest means of being patient.
“They” i.e. those who are described above as being patient “are those on whom are the Salawaat (i.e. who are blessed and will be forgiven) from their Lord” i.e. praise and speaking of their virtue. “and (they are those who) receive His Mercy”, which is abundant. Part of His mercy towards them is that He helps them to be patient, by means of which they attain the reward in full. “and it is they who are the guided ones”, those who know the truth, which in this context refers to their knowledge that they belong to Allaah, that they will return to Him, and they act upon it, and that is their patience for the sake of Allaah.
This verse indicates that the one who is not patient will have the opposite of what they have, so he will be blamed by Allaah and punished, misguided and will suffer loss. How great is the difference between the two groups and how little is the effort of those who are patient, and how great is the pain of those who panic.
These two verses tell us that we should think about calamities before they happen, so as to reduce their impact and make them easier to bear if they do happen, and explain how to respond to them if they happen, which is with patience. And they explain what helps one to be patient, the reward that the patient person will have and they describe the situation of the one who is not patient, which is the opposite of patience. And they tell us that these calamities and trials are the law of Allaah and one can never find any alternative to the law of Allaah, and they describe different kinds of calamities. End quote.
Tafseer al-Sa’di (p. 75).
Think about these words of the Prophet (blessings and peace of Allaah be upon him) and these teachings of the salaf:
it was narrated that there Mother of the Believers, Umm Salamah (may Allaah be pleased with her), said: I heard the Messenger of Allaah (blessings and peace of Allaah be upon him) say: “There is no Muslim who is stricken with a calamity and says what Allaah has enjoined – ‘Verily to Allaah we belong and unto Him is our return. O Allaah, reward me for my affliction and compensate me with something better’ – but Allaah will compensate him with something better.”
She said: When Abu Salamah died, I said: Who among the Muslims is better than Abu Salamah, the first household to migrate to join the Messenger of Allaah (blessings and peace of Allaah be upon him)? Then I said it, and Allaah compensated me with the Messenger of Allaah (blessings and peace of Allaah be upon him).
She said: The Messenger of Allaah (blessings and peace of Allaah be upon him) sent Haatib ibn Abi Balta’ah to me with his proposal of marriage, but I said: I have a daughter and I am of a jealous nature. He said: “As for her daughter, we will pray to Allaah to make her independent of her, and I pray that Allaah will take away her jealousy.”
Narrated by Muslim in his Saheeh (918).
So pray to Allaah to reward you for your calamity and compensate you with someone better than her. Also pray to Allaah for this girl and for all the deceased Muslims, asking for mercy and forgiveness for them.
And Allaah knows best.