While Jacob wasn’t married, he couldn’t be called as Abraham and Isaac, ‘God of Abraham’ and ‘God of Isaac’ (Genesis 28:13). He could be a channel for Zeir Anpin that is the aspect of Right but not to the female aspect that is on the Left.
The Zohar explains that from this we learn that a man who is not married to a woman in this world is not considered complete and cannot be considered a whole on the spiritual levels.
Jacob was different because he was the same above and below. After he got married and had children, the unification below revealed the one above and his connection could be called ‘God of Israel’.
“וַיַּצֶּב שָׁם מִזְבֵּחַ וַיִּקְרָא לוֹ אֵל אֱלֹהֵי יִשְׂרָאֵל”
“And he set up an altar there and called it God, the God of Israel.”
Jacob achieves complete spiritual connection and God promised to protect him and bring him ‘to his land’ that is the aspect the connection to the female, Malchut after he gets married.
“וְהִנֵּה אָנֹכִי עִמָּךְ וּשְׁמַרְתִּיךָ בְּכֹל אֲשֶׁר תֵּלֵךְ וַהֲשִׁבֹתִיךָ אֶל הָאֲדָמָה הַזֹּאת כִּי לֹא אֶעֱזָבְךָ עַד אֲשֶׁר אִם עָשִׂיתִי אֵת אֲשֶׁר דִּבַּרְתִּי לָךְ”
“Behold, I am with you and will keep you wherever you go and will bring you back to this land. For I will not leave you until I have done what I have promised you.”
“וַיִּיקַץ יַעֲקֹב מִשְּׁנָתוֹ וַיֹּאמֶר אָכֵן יֵשׁ יְהוָה בַּמָּקוֹם הַזֶּה וְאָנֹכִי לֹא יָדָעְתִּי”
“Then Jacob awoke from his sleep and said, “Surely YHVH is in this place, and I (אָנֹכִי) did not know it.”
When Jacob woke up from his dream he realized that he didn’t connect to what was revealed to him before at home, which is the holy name ‘אָנֹכִי’ that represents the Shechina. He knew then that by ‘knowing’ (connecting) to the name he would achieve a complete state above and below. That would place him under the protection of the Shechina.
The Amida is at the highest level of our prayers. We do it at least three times a day, every day of the year. At the beginning of it, we mention “God of Abraham, God of Isaac and God of Jacob”. We rely upon and link our connections with theirs so our prayers can ascend to the world of Atzilut (Emanation) when the Light comes to our world.
When we say “Oh God” or “My God”, we should have a proper vessel connected to the Light before we are able to benefit from ‘calling God’.
A proper vessel has the aspect of a female that requires to have unification with the upper levels and receive the Light we need.
For the above reason, men need to get married because they need a proper vessel for unification and manifestation in this world. Women don’t have to because they are vessels.