Is it permissible to have intercourse with one's wife after the Maghrib Adhan for someone who has vowed to fast for three consecutive months?

Legally, fasting is abstaining from things that break the fast from the rise of true dawn until sunset. There is no harm in having conjugal relations with one's wife after sunset, because the fast ends at sunset, as Allah Almighty says: "It has been made permissible for you the night of the fast to approach your wives. They are a garment for you, and you are a garment for them. Allah knows that you used to deceive yourselves, so He accepted your repentance and forgused you. So now, consort with them and seek what Allah has ordained for you, and eat and drink until the white thread of dawn becomes distinct to you from the black thread [of night]. Then complete the fast until night [falls]."