It is the duty of every Muslim to act upon divine commandments himself and exhort others to the same. The first addressees of our call should be our near relations. The Almighty has mentioned in the Holy Qur’an that His great Messengers and Prophets cherished this great virtue of calling the family members and friends to the prayer.
The Qur’an says:
Also mention in the Book Ishmael: He was [strictly] true to what he promised, and he was a messenger [and] a prophet. He used to enjoin on his people the Prayer and Zakah, and he was most acceptable in the sight of his Lord. (19:55-6)
Believing men and women have been called friends and helpers of each other by the Qur’an and are expected to guide each other in religious matters.
However, as to the extent one can go while urging a life partner on observing basic religious duties such as the prayer, it depends upon the individuals involved. The most appropriate and the most effective way is that of persuasion and counseling. A person should try to convince his or her spouse to realize the gravity of the matter and do so very politely with utmost wisdom. The Almighty has guided His messenger to preach politely with wisdom and care. We must not let go of this line of action otherwise our efforts may become counterproductive. Going as far as demanding or threatening with divorce is a question that is very unlikely to produce positive results. What good it will do when the couple get separated? We can better influence a spouse while being united and not after severing marital ties.