I'm a bit confused of what you wrote, sometimes you seem to speak about a boy and sometimes you seem to speak about a girl.
Now any way: We know that Allah is all forgiving therefore you will find some ahadith (hadiths) which advise us never to judge people and never to say that this person would go to jannah or this one to hell. as Allah only knows what is in their hearts and maybe they where big sinners but at the end they made a sincere repentance and expiation and did good deeds and inchallah they might go to jannah. So you should avoid these kinds of thoughts and try to give your friend good advise like telling him to do sincere repentance and expiation... the rest is in the hand of Allah!
- Do they not know that it is Allah who accepts repentance from His servants and receives charities and that it is Allah who is the
Accepting of repentance, the Merciful?
[Surat at-Tawba (9:104)]
- Except for those who repent, believe and do righteous work. For them Allah will replace their evil deeds with good. And ever is Allah
Forgiving and Merciful.
[Surat al-Furqan (25:70)]
- And it is He who accepts repentance from his servants and pardons misdeeds, and He knows what you do.
On the other hand we are all sinners and we all do bad things bad Allah still accepts our dua' and still says:
And when My servants ask you, [O Muhammad], concerning Me - indeed I
am near. I respond to the invocation of the supplicant when he calls
upon Me. So let them respond to Me [by obedience] and believe in Me
that they may be [rightly] guided.
[Surat al-Baqara (2:186)]
Doing istikhara is a known Sunna and it's a prayer followed by a dua' whether Allah accepts it from me you or your friend ... sincerely i could talk about myself: i don't know but i hope so!
Look at the Sahaba some of them have been promised to go to Paradise (jannah) but nonetheless in his fear of God (Allah) was afraid that any little or big mistake he did in his life would trow him into hell!
And Allah knows best!