Praise be to
Allah.
Firstly:
Istikhaarah is mustahabb and is prescribed in Islam, but one does not
necessarily see a dream after it or get an answer as you described. Rather its
effects appear in the matter being made easy. If the matter is made easy and
goes ahead, this is an indication that it is good, in sha
Allah.
Secondly:
The son is not obliged to obey his
parents with regard to marrying a particular woman, but if he does that to
please his parents and make them happy, he will be rewarded for that, so long as
the woman is religiously committed and of good character.
If he gives the matter some thought and
decides that the woman is not appropriate for him, and is afraid that he will
develop resentment towards her or that he will later be forced to divorce her,
then it is better for him to tell his parents frankly about what he feels and
to apologise to them for cancelling his engagement.
This is better than going ahead with something he does not really want.
We advise you to think long and hard and
to examine your fiancée’s characteristics, both positive and negative, before
taking the decision to cancel the engagement. If she is religiously committed
and of good character, and has no faults other than what you mention about her
hair, then this can be dealt with. And a woman may be beautiful or acceptable
despite that problem.
But we also think that you should delay
going ahead with the marriage until you have put your mind at rest about that
decision.
You should offer a lot of du‘aa’ (supplication) and ask Allah to guide you to that
which is best in this world and in the Hereafter.
See also the answer to question no. 26852
And Allah knows best.