I do not know your friend’s exact situation so only an answer on priniciple can be given. So consider the following points.
1. It is not an obligation upon Allah to give anyone what they ask for. Everything has always been a favor from Allah, one should be grateful that the Lord of the Universe even decided to take time to listen to us in the first place.
2. It is said that Allah will answer every dua but not necessarily in the way you want because point 1.
3. Point 2 exist because Allah has a better plan and it is a test of how much man is willing to trust his Lord.
4. This world is based also on a principle of cause and effect. If I don’t prepare for a test always, then I will by that priniciple will always fail it unless I make some changes in my preparation. If I am not capable of passing a test because of some weakness then until the weakness exist, it is likely that I will never pass that test. Allah may not always intervene, He does sometimes but not always because He doesn’t break world’s rules occasionally. You will have to go through this priniciple.
5. Because of how powerless we are against the reality of Allah’s Will, only thing you can do is just look at yourself, see what mistakes we are making, try a different approach, take a different path. It is may likely that Allah does not want people to go where they are headed or perhaps they are not yet ready to reach the destination so sometimes Allah will stop your path until you are ready.
6. The story/vision of Hazrat Musa (AS) and Al-Khidr in the Qur’an talks about how Allah may seem to do things that man doesn’t want but once the wisdom is shown, one can’t help but simply trust their Lord because He always has what is best for His servants when the final outcome of His plan is revealed.