How can one get rid of the idea of marriage that has become an obsession negatively affecting studies and worship, especially with imagining being pursued for marriage proposals and focusing on bearded men?

The cure for thinking about marriage is marriage for those who can afford it; otherwise, it is fasting, which is a protection against zina (unlawful sexual intercourse). A woman should not refuse suitable suitors, and if she does not find a suitable one, she may ask her guardians to search for a suitable husband for her. The sister who asked the question should accept a suitor who possesses religiosity and good character. If she does not find one, she should ask her guardian to propose her to someone whom he deems righteous and upright. As for the obsessive thoughts, they might be due to self-talk and a longing for marriage. One must disregard these thoughts, seek refuge in Allah from Satan, and regularly recite adhkar (remembrances of Allah) and the Quran.