Yet many humans don't mate for life, throughout human history. So is that their biology?
Yes? Individuals within a species vary. Nature isn't precise, it's a random walk.
Also, desires can change over a lifetime. Some correlate strongly with hormones and others with life experiences.
Big difference between mating and marriage. Lot of marriage where mating is not happening but couples cannot separate because of social/legal/emotional ramifications.
yeah marriage is more of a business deal than anything else