Is it permissible for him to ask Allaah for the girl who died and to whom he wanted to propose marriage to let her be his bride in Paradise?

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”

[al-Baqarah 2:155-157]

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.