In the Vedic civilisation it was the custom that the husband became a natural guru to his wife. However, Srila Prabhupada also speaks of times, when it can be the other way around. SP Letter to: Silavati, New Vrindaban, 14 June, 1969
"My Dear Silavati,
Please accept my blessings. I thank you very much for your letter dated June, 1969, and I have carefully noted the contents therein. Regarding the suggestion that you remarry, I have never suggested such thing, so you need not trouble yourself with this. As I have told you in Los Angeles, I wish that the mother's who have no husband at present should not remarry, but should dedicate their time to seeing that their children are brought up very nicely in Krishna Consciousness. Your boy, Birbhadra, has just arrived here, and he will be taken care of by Kirtanananda Maharaja. Satyabhama Dasi is in charge of educating the children in New Vrindaban, and she is very qualified to do this because she is educated and works very nicely with the children. So there is no difficulty at present in this regards, and as you are so nicely engaged in your activities in Los Angeles, you should continue as you are now doing. Your description of the course you are giving to the interested girls about the role they play in Krishna Consciousness is very nice, and I am pleased that you have begun this project. Actually the role of all conditioned souls is the same; to chant Hare Krishna, tell others to chant, perfect our lives in Krishna Consciousness, and to go back to Godhead when this body is finished. Now if you can induce all the women of Los Angeles to place an altar in their homes and help their husbands have peaceful, happy home life in Krishna Consciousness, that will be very great service for you. The actual system is that the husband is Spiritual Master to his wife, but if the wife can bring her husband into practicing this process, then it is all right that the husband accepts wife as Spiritual Master. Caitanya Mahaprabhu has said that anyone who knows the science of Krishna, that person should be accepted as Spiritual Master, regardless of any material so-called qualifications; such as rich or poor, man or woman, or brahmana or sudra. So if you can show the women of the community how to help their husbands and children to perfect their home life, and all aspects of life, in Krishna Consciousness by chanting, aratrik ceremonies, and eating Krishna prasadam, then you will improve the conditions of the neighboring communities to an incalculable extent. So try for this as far as possible. I already have practical experience that many of the American girls and boys are very intelligent and qualified to take up this sublime movement. We simply have to instruct them nicely, and surely many will understand that here is such a nice thing and they must take to it. So I am very pleased with the nice efforts you are making. I hope this will meet you in good health.
Your ever well wisher,
A.C. Bhaktivedanta Swami"