companion; partner; spouse
彼女は私の生涯の伴侶でした。
She was my lifelong companion.
彼はついに生涯の伴侶を得た。
He finally found his lifelong partner.
仲人は披露宴で二人が良き伴侶となるよう願った。
The matchmaker wished at the reception that the two would become fine lifelong partners.