Is the way my friend grieving based on her culture rather than religion?

Months ago I posted about a funeral I was heading for my Qatari friend. I was asking for tips on what to do.

I noticed later that my friend wasn't crying or being sad at all. She was shocked and sad that the relative was gone at the moment, but after the funeral, she just never seemed to be fazed by it. Her lifestyle stayed consistent and acted the same way she used to before it happened. I asked her about it and she told me that the relative is in heaven and won't go to hell because they were a good person because they earned so many good deeds (they donated millions of euros, housed people, educated people, etc) but I thought Muslims couldn't say who could and couldn't go? I know actions determine it but I would hear from them that God is the judge and you should avoid those assumptions.

She did not show sadness for more than 2 days. Her life stayed the same way, she looked happy and cheerful, etc. I don't have many arab friends to ask this, but I do know grief affects everyone differently, but it is her whole family who is acting like this. Only the mom seemed sad for around a month. I know people hide grief but I have never seen it be done this way before.