A spouse is your companion, your mate, your partner. In ye olden times, spouse was used as a verb meaning “to marry,” but nowadays, it functions as a noun referring to either husband or wife.
Your spouse is often called "your better half." What we call adultery used to be referred to as spouse-breach in the early 13th century. American pediatrician Benjamin Spock said, “The surest measure of a man's or a woman's maturity is the harmony, style, joy, and dignity he creates in his marriage, and the pleasure and inspiration he provides for his spouse.” So, avoid that spouse-breaching at all costs, and till death do you part.