The believer’s family joining him in Paradise

Will the people who go to Heaven be reunited with their loved ones who
go to Hell? Is it possible to take loved ones out of Hell, since all
requests in Heaven are granted (assuming they know about their fate)?
Can we also be reunited with our Loved ones in this world who are
non-mahrum to us? This includes those that we loved but could not
marry.
Praise be to Allaah.
Firstly, you say, "does this include those whom we loved but could not marry?"
The answer to this is thatit is not permissible for aMuslim man to
form a relationship with a non-mahram women, or for a Muslim woman to
form a relationship with a man or to have an emotional attachment
tohim, except for her husband. See Questions nos. 9465, 5445, 1200.
Secondly, you say, "Will the people who go to Heaven be reunited
withtheir loved ones who go to Hell?"
The answer is, yes, the people of Paradise will be reunited with their
loved ones who went to Hell, if they were believers in Tawheed (the
oneness of Allaah). That will be by virtue of their intercession for
them to be brought forth from Hell and admitted to Paradise. The
evidence for that was narrated by al-Bukhaari in Kitaab al-Tawheed,
no. 7440:
It was narrated that Abu Sa'eed al-Khudri said: "We said, 'O Messenger
of Allaah! Shall we see our Lord on the Day of Resurrection?' He said,
'Do you have any difficulty in seeing the sun and the moon when the
sky is clear?' We said,'No.' He said, 'So you willhave no difficulty
in seeing your Lord on thatDay, just as you have no difficulty in
seeing the sun and the moon (in a clear sky). …Then the bridge will be
laid acrossHell.' We said, "O Messenger of Allaah! What is the
bridge?' He said, 'It is a slippery (bridge) on which there are clamps
and (hooks like) thorns which are wide at one side and narrow at the
other and have bent ends. A plant with such thorns is found in Najd
and is called al-Sa'daan. Some of the believers will cross the bridge
as quickly as the wink of aneye, some others as quick as lightning, a
strong wind, or fast horses or she-camels. So some will be safe
without any harm; some will be safe after receiving some scratches,
and some will fall down into Hell (Fire).The last person will crossby
being dragged (over the bridge). You (Muslims) cannot be more pressing
in claiming from me a rightthat has been clearly proved to be yours
than the believers in interceding with Almighty Allaah for their
(Muslim) brothers on that Day, when they see themselves safe.
They will say, "O Allah! (Save) our brothers (for they) used to pray
with us, fast with us and also do good deeds with us." Allah will say,
"Go and take out (of Hell) anyonein whose heart you find faith equal
to the weightof one (gold) Dinar." Allah will forbid the Fire to burn
the faces of those sinners. They will go to them and find some of them
in Hell (Fire) up to their feet, and some up to the middle of their
legs. So they will take out those whom they will recognize and then
they will return, and Allah willsay (to them), "Go and take out (of
Hell) anyonein whose heart you find faith equal to the weightof one
half Dinar." They will take out whomever they will recognize and
return, and then Allah will say, "Go and take out (of Hell) anyone in
whose heart you find faith equal to the weightof an atom (or a small
ant)," and so they will take out all those whom they will recognize.'"
Abu Sa'eed said, "If you do not believe me, read, if you wish,
'Surely, Allaah wrongs not even of the weight of an atom(or a small
ant), but if there is any good (done), He doubles it...' [al-Nisaa'
4:40 – interpretation of the meaning]." The Prophet (peace and
blessings of Allaah be upon him) said: "Then the Prophets and Angels
and the believers will intercede, and (last of all) the Almighty
(Allah) will say, 'Now remains My Intercession. He will thenhold a
handful of the Fire from which He will take out some people whose
bodies have beenburnt, and they will be thrown into a river at the
entrance of Paradise,called the water of life. They will grow on its
banks, as a seed carried by the torrent grows…"
But for those who believed in shirk, no intercession will benefit
them. Allaah says (interpretation of the meaning):
"Verily, Allaah forgives not that partners should be set up with Him
(in worship), but He forgives except that (anything else) to whom He
wills"
[al-Nisaa' 4:48]
Note that intercession is of two types:
"The first type is the kindof intercession that is the exclusive
preserve ofthe Messenger (peace and blessings of Allaah be upon him),
which is of varying kinds, the greatest of which is the Great
Intercession in the Station of praise and glory (al-maqaam al-mahmood)
which Allaah has promised to him in the aayah (interpretation of the
meaning):
'And in some parts of thenight (also) offer the Salaah (prayer) with
it (i.e. recite the Qur'aan inthe prayer) as an additional prayer
(Tahajjud optional prayer Nawaafil) for you(O Muhammad). It may be
that your Lord will raise you to Maqaam Mahmood (a station of praise
and glory, i.e., thehonour of intercession on the Day of
Resurrection)'
[al-Israa' 17:79]
This intercession means that he will intercede forthe people who are
standing on the Day of Resurrection, so that the distress they are
suffering will be reduced for them.
The second type is general intercession on the part of the Messenger
(peace and blessings of Allaah be upon him) for all the believers.
This is of various kinds:
(i) Intercession for those who
deserve Hell, so thatthey will not enter it. This is indicated by the
words of the Messenger (peace and blessings of Allaah be upon him),
"There is no Muslim who dies and forty men who do not associate
anything with Allaah pray the funeral prayer for him, but Allaah will
accept their intercession for him." (narrated by Muslim, 2/655).
(ii) Intercession for those who
have entered Hell, so that they will be brought forth from it. It was
narrated that Abu Sa'eed al-Khudri said: "The Messenger of
Allaah(peace and blessings of Allaah be upon him) said: 'By the One in
Whose hand is my soul,
You (Muslims) cannot be more pressing in claiming from me a rightthat
has been clearly proved to be yours than the believers in interceding
with the Almighty for their (Muslim) brothers on that Day, when they
see themselves safe.
They will say, "O Allah! (Save) our brothers (for they) used to pray
with us, fast with us and also do good deeds with us." Allah will say,
"Go and take out (of Hell) everyone whom you recognize." Allah will
forbid the Fire to burn the faces of those sinners. So they will bring
forth many peoplewho were in the Fire upto their calves or their
knees." (Narrated by Muslim,269)
(iii) Intercession to raise the
believers in status. This isbecause of the du'aa's ofthe believers for
one another, as the Prophet (peace and blessings of Allaah be upon
him) said, making du'aa' for Abu Salamah: "O Allaah, forgive Abu
Salamah, raise him in status among those who are guided, make his
grave spacious for him and fill it with light, and protect his family
who are left behind." And there is thedu'aa' for intercession asthe
Prophet (peace and blessings of Allaah be upon him) said: "There isno
Muslim who dies and forty men who do not associate anything with
Allaah pray the funeral prayer for him, but Allaah will accept their
intercession for him."
Reference: al-Qawl al-Mufeed, vol. 1, p. 332