Pair bonding is a biological program not a cultural construct
Despite a colorful array of cultural differences, humans everywhere fall in love, attach emotionally for long periods, and feel betrayed when mates are unfaithful. These behaviors are innate, not the products of random cultural influences. To make this point another way: Most mammals don't tattoo their mates' names on their bums, and are not subject to fits of jealous rage.
Human Brains Are Built to Fall in Love, an earlier post, explained that pair bonding behaviors have neurobiological mechanisms behind them. Now, there's more research evidence of our underlying pair-bonding programming.