Is it advisable to marry a young man who initially did not meet the required religious standards, but then showed improvement and religious commitment after the first rejection, only to violate some of the Islamic guidelines set by the suitor after agreeing to the second proposal, which raises her concerns about future incompatibility?

You are right to be wary of making a mistake in choosing a husband, for a Muslim woman must be careful in whom she chooses as a husband to ensure the stability and continuity of marital life. The suitor should be someone whose religiosity and character are pleasing, as stated in the Prophetic Hadith: "If someone whose religiosity and character you approve comes to you seeking marriage, then marry him. If you do not do so, there will be tribulation on earth and widespread corruption." Al-Hasan al-Basri said: "Marry her to a man who fears Allah, for if he loves her, he will honor her, and if he dislikes her, he will not wrong her."

Therefore, it is not advisable to agree to marry someone whose religiosity and character are not evident as pleasing, and one should not be deceived by what the suitor says. Rather, it is better to inquire about him from those who have lived with him and dealt with him. If they praise him, then there is no harm in accepting him as a husband; otherwise, it is preferable to leave him. One should also perform Istikhara (prayer for guidance) and entrust the matter to Allah Almighty to choose what is best.