Is it considered disobedience to parents for a young man to insist on breaking off his current engagement and proposing to another girl, despite his parents' opposition and his father's threats of disinheritance, especially since the young man works and lives in a city far from his family, and the other girl has promised to try and convince her family despite their previous refusal?

The presence of parents is a blessing, and one must treat them with kindness, especially in their old age, as Allah Almighty says: "And your Lord has decreed that you worship none but Him. And to parents, show kindness. If one of them or both of them attain old age with you, say not to them a word of disrespect, nor repel them, but address them in terms of honor. And lower to them the wing of humility out of compassion and say, 'My Lord, have mercy upon them as they brought me up when I was small.'" [Al-Isra: 23-24].

We advise you to accede to your parents' wishes and leave this girl, as there are social differences between you that could lead to the collapse of family stability. Her family also rejected you previously, and there is nothing to confirm that their opinion has changed.

Regarding the girl you are engaged to but do not feel at ease with, you can break off the engagement as long as there are reasons. If you do not feel at ease with her and fear that you might wrong her, you can leave her and search for another with whom you feel comfortable.