To what extent is marriage valid after sins, separation, and returning to each other? And is it permissible to marry again without khulʿ and without the wife receiving the mahr?

If a married couple apostatizes from Islam after consummating their marriage and then returns to it, their return before the expiration of the waiting period (iddah) keeps the marriage valid. However, if their return is delayed until the iddah expires, the marriage is dissolved according to the majority of jurists. The iddah for a pregnant woman is until she gives birth, and for a non-pregnant woman, it is three menstrual cycles. If you wish to separate from him, you can request a divorce (talaq) or a khul'. Khul' is permissible for a legitimate reason, such as the wife's dislike of her husband, and it involves her relinquishing her dower (mahr) or a part of it. After a talaq or khul', you observe the prescribed iddah, and then you can marry another. If the iddah expired before both of you returned to Islam, or before your husband returned, then the marriage is dissolved, and you are permitted to marry someone else. You must purify your womb with one menstrual cycle before remarrying, unless you are pregnant, in which case intercourse is not permitted until you give birth.