In the context of a marriage decision, a 'Faal' from the Quran was positive, but an Istikhara done later later yielded a negative result. What should one do?
Bismihi ta'ala
In the context of marriage, istikharah should only occur if someone is two-minded about two different proposals at once, both being equal.
For marriage, you should do a background check on the person, research about them, look at compatibility, try to understand who they are, their family especially, and then consult with well-informed or experienced people.
How actually religious are they? How is their akhlaq and what are their moral standards? These are the two primary questions you must have an answer to as well.
It's only after this that you evaluate the situation, and see whether or not you are still confused and two-minded, in which case you can do istikharah.
Faal is different to istikharah. Faal is trying to find out what will happen, whereas istikhara is is about whether you should go ahead or not.
In any case, these stages should be pursued, and if you are convinced, and done all your required work, you do not need to resort to istikharah.
And Allah knows best