A male without a female is called half a body.
A good relationship makes the partners more complete people
("For Rabbi Shimon said: The union of male and female is called one; where the female is present, it is called one. What is the reason? Because a male without a female is called half a body." – Zohar, Volume 3, Leviticus 7b)
Translation
Expression (Hebrew)
זָכָר בְּלִי נְקֵבָה נִקְרָא חֲצִי גּוּף
Definition (Hebrew)
זוּגִיּוּת טוֹבָה בְּחַיֵּי הָאָדָם עוֹשָׂה אוֹתוֹ אָדָם שָׁלֵם יוֹתֵר.
("דְּאָמַר רַבִּי שִׁמְעוֹן זְוָגָא דְּדָכַר וְנוּקְבָּא אַקְרֵי אֶחָד, בַּאֲתַר דְּנוּקְבָּא שְׁרֵא, אֶחָד אַקְרֵי, מַאי טַעֲמָא בֵּגִין דְּדָכַר בְּלֹא נוּקְבָּא פֶּלֶג גּוּפָא אַקְרֵי" – זֹהַר כֶּרֶךְ ג וַיִּקְרָא ז ע"ב)