Parents need to equip sons to leave home - Gen 2:24 - by teaching them about marriage, from 1 Cor 6-7; Leviticus 18; Mark 6:18; 1 Cor 7:39, and by living it themselves. Marriage is an earthly, covenantal union, not an eternal, metaphysical union. Encourage and channel boys' masculinity, don't discipline it out of them. Else they'll be too timid to intervene in a girl's life. A boy may hear "no" from her father; he should have been learning long before this from his parents to cope well with getting knocked down. Parents also instill self-control early, so the boy can control himself sexually, needing to wait several years from desire to fulfillment.
Young men should always assume the burden of proof in moving the relationship forward, explaining to her father and her his plans, Lord willing. He doesn't press for a commitment from her ahead of time, using God's will as leverage to get it. He protects her from the risk of initiating, relationally. He lets her respond to him, and if it is no, he protects her from having to explain why. Her dad will be her main protection in this, and the young man protects her by going through him. He is a gentleman.