Are the repeated obstacles I face when pursuing something, after performing Istikhara and relying on Allah, considered a sign from Allah that this matter should not be completed, and is this view correct in Islam?

The believer is required to employ legitimate means while relying on Allah and striving for what benefits him. If he is not successful in a matter, he should not lament, but rather believe in Allah's divine decree and predestination, and say: "Allah has decreed and what He wills, He does." For there may be good in prevention, as Allah Almighty said: {But perhaps you hate a thing and it is good for you; and perhaps you love a thing and it is bad for you. And Allah Knows, while you know not.} [Al-Baqarah: 216]. The believer must know that every calamity is decreed, and his duty is to employ means with reliance on Allah and patience when destiny occurs. As for obstacles, they do not necessarily mean that the matter is not decreed; rather, one must rely on Allah and strive. If the matter is not accomplished, then he knows that it was not decreed for him, and he must not regret by saying "if only," because it opens the door to the work of Satan, while being diligent in supplication, exertion, and striving. The prayer of Istikhara (seeking guidance from Allah) is recommended, and whoever seeks guidance from Allah will only encounter good.