RSRH Zatzal says that if Yitzchok’s need for a wife is similar to the need of a mother, then it must have been in Ruchaniyus, unlike a Goy who’s main Inyan (priority) is Ta'avos. It is interesting that a big Seuda was made: ב יוֹםְְּּהִּ גָׂמ לְּא תְְּּיִּצ חָׂ קְְּּלךְּכאְּחְּ on the day that Yitzchok finished nursing from his mother. What is so special about being weaned from a mother? We can suggest that not needing to rely on a “human” brings a person more independence, and he needs to rely more on Hashem. **
The Chovos Halvavos in Shaar HaBitachon mentions how with each progressing stage in life, a person needs Hashem more and more, and his parents less and less. However, in Ruchaniyus it seems that a mother is invaluable, and she can do what a father cannot do (usually). Notice how Sara Imeinu saved Yitzchok from the bad influence of Yishmael, and Avraham Avinu did not. Similarly, we find Rivka Imeinu saving Yaakov from Eisav, and saving her husband from giving Eisav the Brachos, Chas V'shalom! ***
And at a Chasuna, the Kalla wears white which symbolizes purity. Chazal say about a wife that: ד ג מ ש לוֹת ב ינוּ נ צ מ וּילוֹת אוֹת נוּ מ ן אט ח ה יבמותְּסגְּא she is a Shemira (protection) to save her husband from the filth of the outside world. She supplies his Gashmiyus'dik needs, and she is also a: שוֹמ ר guard to protect the children from outside influences. I spoke to a: לה ְּנְַּמ ְּ principal of a big Yeshiva, and he told me that it’s always the mothers who call with tremendous concern when their children are being exposed, Rachmana Litzlan. ****
