Can the failure to achieve what a person desires be attributed to the will of God, even though the person believes that what they desire is in their best interest?

Nothing of the servants' deeds falls outside the power and will of Allah. Allah Almighty says: "And you do not will except that Allah wills, the Lord of the worlds," and He says: "Indeed, We have created all things with a [divine] decree." When asked about divine decree (Qadar), the Messenger of Allah, peace and blessings be upon him, said: "Rather, it is what the pen has dried upon and what the decrees have been set for, and everyone is facilitated for what he was created for."

When we ask, "Do we attribute our undesirable actions to divine decree (Qada' and Qadar)?" Yes, for divine decree is built upon pillars, one of which is that whatever Allah wills comes to be, and whatever He does not will does not come to be. This is the universal, predetermined will that must occur, whether Allah loves it or does not love it according to religious law. An example of this is His saying, the Most High: "And my advice will not benefit you if I should intend to advise you, if Allah intends to put you in error."

We must know that Allah does nothing except with wisdom. This wisdom may not be apparent to the created being, but it is sufficient for a Muslim to reflect on His saying, the Most High: "But perhaps you hate a thing and it is good for you; and perhaps you love a thing and it is bad for you. And Allah knows, while you know not," and the saying of the Prophet, peace and blessings be upon him: "Wondrous is the affair of the believer, for there is good for him in every matter. If he is afflicted with ease, he is grateful, and that is good for him. And if he is afflicted with hardship, he is patient, and that is good for him."