All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, is His slave and Messenger.
It is forbidden for a man to prevent a woman under his guardianship from marriage if a suitable suitor proposed to her. If he does so, his right to guardianship (over her in the marriage contract) is waived and transferred to the next eligible male relative entitled to her guardianship. Ibn Qudaamah said in Al-Mughni: “If her closest guardian unjustifiably prevents her from marriage, the guardianship is transferred to the farther relative entitled to her guardianship. This opinion was stated by (Imam) Ahmad. Another opinion was narrated on his [i.e. Imam Ahmad] authority stating that the guardianship is transferred to the ruler…” [End of quote]
He also said in Al-Mughni: “The meaning of (the Arabic word) ‘Adhl is preventing a woman from marriage to a suitable suitor when she requests it.”
If it is possible to give advice to the guardian to convince him (to change his attitude), then it is better, so we advise you to seek the help of wise people whom your father respects to try to convince him to accept, and thus the problem would be eliminated from the root. This also has the added benefit of earning the pleasure of your father, in which lies abundant good and virtues.
Allah Knows best.