God does not “need” a female companion. To say God needs is to say He is lacking in something. He is God. He is not lacking in anything.
Catholics believe in three persons but one God. The Jewish people believe in one God because God himself revealed that to them.
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Christians are baptized in the name of the Father and of the Son and of the Holy Spirit: not in their names**,55 for there is only one God, the almighty Father, his only Son, and the Holy Spirit: the Most Holy Trinity.
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Following this apostolic tradition, the Church confessed at the first ecumenical council at Nicaea (325) that the Son is “consubstantial” with the Father, that is,
one only God with him.66 The second ecumenical council , held at Constantinople in 381, kept this expression in its formulation of the Nicene Creed and confessed "the only-begotten Son of God, eternally begotten of the Father, light from light, true God from true God, begotten not made, consubstantial with the Father."67
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Before his Passover, Jesus announced the sending of “another Paraclete” (Advocate), the Holy Spirit. At work since creation, having previously “spoken through the prophets,” the Spirit will now be with and in the disciples, to teach them and guide them "into all the truth."68 The Holy Spirit is thus revealed as another divine person with Jesus and the Father.
The dogma of the Holy Trinity
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The Trinity is One. We do not confess three Gods, but one God in three persons, the "consubstantial Trinity."83 The divine persons do not share the one divinity among themselves but each of them is God whole and entire: "The Father is that which the Son is, the Son that which the Father is, the Father and the Son that which the Holy Spirit is, i.e., by nature one God."84 In the words of the Fourth Lateran Council (1215): "Each of the persons is that supreme reality, viz., the divine substance, essence or nature."85
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The divine persons are really distinct from one another. "God is one but not solitary."86 “Father,” “Son,” “Holy Spirit” are not simply names designating modalities of the divine being, for they are really distinct from one another: "He is not the Father who is the Son, nor is the Son he who is the Father, nor is the Holy Spirit he who is the Father or the Son."87 They are distinct from one another in their relations of origin: "It is the Father who generates, the Son who is begotten, and the Holy Spirit who proceeds."88 The divine Unity is Triune.
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The divine persons are relative to one another. Because it does not divide the divine unity, the real distinction of the persons from one another resides solely in the relationships which relate them to one another: "In the relational names of the persons the Father is related to the Son, the Son to the Father, and the Holy Spirit to both. While they are called three persons in view of their relations, we believe in one nature or substance."89 Indeed "everything (in them) is one where there is no opposition of relationship."90 "Because of that unity the Father is wholly in the Son and wholly in the Holy Spirit; the Son is wholly in the Father and wholly in the Holy Spirit; the Holy Spirit is wholly in the Father and wholly in the Son."91
I explained it best to my 1st graders " I am one person and at the same time I am Mother, daughter and I have a spirit." That is as close as I can get to explaining the Trinity.
usccb.org/catechism/text/pt1sect2chpt1art1p2.htm