All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Bashfulness is all goodness and brings only what is good as the most truthful human; Prophet Muhammad, sallallaahu ‘alayhi wa sallam, told us. As for what you have mentioned about that person, i.e. introversion, staying away from people, fear of failure and the like, then they all have nothing to do with bashfulness. Rather, it is a form of weakness and psychological disorder that should be treated through seeking the help of Allaah The Almighty, putting full trust in Him and doing a great deal of asking Him for forgiveness. One should also bear in mind the statement of the Prophet, sallallaahu ‘alayhi wa sallam: "A strong believer is better and is more beloved to Allaah than a weak believer, but there is good in both of them. Strive to attain that which will benefit you and seek help of Allaah and do not feel helpless. However, if a misfortune befalls you, do not say: "If I had done such and such, it would have been better'', but rather say: ''Allaah predestined so, and whatever Allaah wills will happen”, as the subordinating conjunction ''if'' opens the doors of the devil..’" [Muslim]
If there is a need to visit some trustworthy psychiatrists, then he should do so. To get more benefit, please refer to Fataawa 82537 and 133933.
On this occasion, we would like to advise parents to beware of strong rebuke of their children at the times of failure for this causes many bad consequences. Verily, we have in the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, the best example. It was narrated that Anas said: "I served the Prophet, sallallaahu ‘alayhi wa sallam, for ten years and he never said to me “Uff!” (a word of contempt) or “Why did you do such and such?” or “Why did you not do such and such?” [Al-Bukhari and Muslim]
Furthermore, we would like to draw the attention to observing dutifulness to parents, even if they mistreated their child. For more benefit, please refer to Fataawa 82254 and 84942. This is the answer of the first question.
As for the answer of the second question, it is not obligatory for one to obey his stepmother. However, one should be dutiful to her as this is a form of observing dutifulness towards the father. This matter is greatly confirmed in your friend's case especially because she is his maternal aunt who has the same status as the mother as stated in the honorable Sunnah. Actually, it is strange to find such jealously between the son and his stepmother to get the attention of the father. The son should give up such kind of jealousy and not compete with his maternal aunt who is also his stepmother. Anyway, the good wisdom of the father may be a solution for such jealousy or may lighten its effects.
To know the answer of the third question, kindly refer to Fataawa 130942 and 89154.
Allaah Knows best.