Is it obligatory to complete and affirm the engagement after repeated excuses from the girl's family, knowing that the young man has performed Salatul-Istikhara and felt uneasy?

In choosing a wife, her religiosity and character should be considered. If the girl is religious and of good character, be patient and do not rush to break off the engagement. The lack of comfort after performing Istikhara is not an indication that the marriage is not good; rather, Istikhara can be repeated, and the matter can be entrusted to Allah. The Hadith (definition) does not state that Istikhara results in a feeling of ease in the heart or a vision, and sometimes, the person performing Istikhara may not find comfort even after repeating it. If you perceive hesitation from the girl's family and it becomes highly probable that they do not wish to complete the marriage, then there is no harm in breaking off the engagement. Do not regret it, and ask Allah to facilitate something better for you, for Allah says: "And perhaps you dislike 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).