Salaam,
Personally, I believe the "sadness" is just her "personality", she is just not a "smiley" person. Many people who has met her in person, say she is a humble individual. From what I read, she is a private person and may be seen as "aloof" by the Bruneians. Also it is hard to mingle when people do not give you a chance.
IMHO if there is another marriage in the future for the Sultan, it is best for him to marry a fellow Bruneian accepted by his subjects.
Azrinaz is an educated lady and I believe she can live her life with dignity, in her phase outside of the palace. I believe it was the Sultan that fell in love with her at first sight and became her "fan" following her news reading on Malaysian TV. I believe it was difficult for her to say no when he asked for her hand in marriage. As one of the richest man and the most powerful in his nation, I am sure he can have his picks of candidates, more beautiful and lovelier, but somehow he chose Azrinaz. It was her destiny to marry the Sultan.
We muslims believe, our destiny lie with God. Their marriage life has ended, and only these two individuals know the reason for their divorce. It must be a difficult decision for the Sultan whom I see as a very just, kind and fair individual.
With regards to the "tudong", she is wearing the "selendang" in some formal occasions. I don't think she is fully "hijabi" yet, perhaps she will in the future.
I also know many Bruneian friends who only wear the tudong in Brunei, but when they are abroad they do not. Except for Queen Saleha and all her daughters who are in full hijab all the time, you will see Mariam (the ex-wife) and her two daughters do not when they are in London, so does Sarah the CP's wife when she is abroad.
With Malaysians if they are not fully "hijabi" they tend to wear the "selendang" at formal occasions. However, once they decided to be fully covered, they will wear the full hijab (tudong = means "covering") no matter where they are, in Malaysia or abroad.
I hope this explains.
Wasalaam.
i think the main reason why people do not like this marriage is because the fact that the marriage was held in secret, & us Bruneians only knew about the marriage when the news leaked out in Malaysian newspapers. only then the wedding was officially announced.
From my observation, even PRI Saleha did not know about it. I just came back from Paris and someone who just accompanied PRI Saleha on a shopping trip in Milan, asked me about her and the marriage when the news first leaked in Malaysia. I had to google to find out about Azrinaz coz I have not heard of her as I don't watch the Malaysian news much. I believe it is the Sultan's decision to keep the matter private to respect PRI and probably due to the big age gap, IMHO. I do not think Azrinaz had any say in such matter, for she can't even announced the name of the groom in her personal wedding invitations to close friends and families. But since it was held at the Rumah Awang Alak Betatar (the Brunei Royal residence in Malaysia) in Jalan Ampang, eventually the newshounds figured it out.
I want to add another point. You said some say it was Azrinaz's fault. Generally when middle aged or elder men get married with much younger woman, they expect them to be too mature and down to earth for their age. They compare them with their previous wives or partners who are around at the same age as themselves. So they feel disappointed at the end. But they have to make a decision between a beautiful vibrant young lady and a mature experienced lady. You can't combine the comforts of two kinds in one person. If you insist on turning a young woman into a fifty year old woman in terms of behavior, they only create a Frankenstein. 
. Jewels? Who could be thinking about jewels right now???
