Am I allowed to supplicate against a young man who proposed to me, then it became clear that he had lied to and deceived me and my family, or would that displease Allah?

If a man proposed to you, but was manipulative and not serious about completing the marriage, then he has wronged you and transgressed the limits of Allah by speaking and corresponding with you. It is permissible to supplicate against the oppressor to the extent of his oppression, without transgression, but forgiveness is better. We advise you to refrain from supplicating against him and strive instead to pray that Allah grants you a righteous husband. It must be noted that a suitor is considered a stranger to the woman he is proposing to until the marriage contract is concluded.