Does seeking a divorce in order to enable marriage and procreation fall within the scope of the Prophet's (peace be upon him) prohibition, and is abandoning treatment, out of despair of healing, unlawful after exhausting all means?

A woman is not permitted to seek a divorce from her husband except for a valid reason, such as a bad marital relationship or intense hatred that prevents her from fulfilling her husband's rights. Whoever seeks a divorce without a valid reason, the scent of Paradise will be forbidden to her. If your life is stable and your husband is patient regarding not having children, then it is not permissible for you to seek a divorce merely out of fear that he might marry in the future, as this is an assumption that might change.

As for seeking medical treatment and looking for ways to conceive, it is permissible or even recommended. However, according to the majority of jurists, medical treatment is not obligatory unless it is essential for the preservation of life. Therefore, there is no blame upon you if you forgo treatment and accept your situation, but do not despair of Allah's mercy.