What is the interpretation of the fact that the Istikhara prayer indicated good in a suitor who later turned out to be unsuitable, and what is the way to have prayers answered for marriage to a righteous young man?

What a sleeper sees in a dream has no legal effect on rulings, and it is not permissible for a woman to be alone with a man who is a stranger to her, even if he is her fiancé. Rather, it is permissible for a fiancé to look at the woman what would lead him to marry her. And her speaking to him on the phone, if it is not out of necessity and without a submissive tone in her speech, then it is forbidden. It is advised to fear Allah, be patient, and practice chastity until a righteous husband comes, for "Whoever desires the reward of this world - then with Allah is the reward of this world and the Hereafter."