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.
Ghusl is only required when maniy (semen) gushes out accompanied by feelings of pleasure or when the two circumcised parts (al-khitanan) meet (i.e. when the tip of the penis disappears completely in the vagina). Ghusl is not required by only arousal or by the emission of prostatic fluid (madhiy). It is not obligatory to perform ghusl if the maniy was emitted without desire. One who doubts whether the discharge was maniy or something else, then he can choose: Either he considers it maniy, in which case, ghusl from janaabah (impurity following sexual activity) is required, or considers it madhiy, then it is sufficient to wash the traces of madhiy from the body and clothes. Giving the option to choose in this case is the view of Al-Shaafi'i's School of Fiqh (jurisprudence), and our fatwa is issued based on that.
As for the Hanafi School of Fiqh, if there are doubts about the discharge, then it needs to be discussed in detail and cannot be covered in this fatwa, especially in the English language. For those who are able, they can refer to the books of Hanafi School of Fiqh to study their view in detail. As for supplication, we do not know a specific supplication for what you asked about, but one can supplicate for whatever he wants of the good of this world and the Hereafter. Among the supplications that one can supplicate with is the following supplication which the Prophet used to say: “O Allah, I ask You guidance, piety, chastity, and sufficiency.” [Muslim] And what was narrated by Ahmad, At-Tirmidhi, and others that Shakal ibn Humaid said: “I came to the Prophet and said: 'O Messenger of Allah, teach me a way of seeking refuge so that I may seek refuge by it.” He said: “So he took my hand and said: 'Say: O Allah, indeed I seek refuge in You from the evil of my hearing and the evil of my sight, and the evil of my tongue and the evil of my heart, and from evil arising from my sexual passion.”
Allah knows best.