Engagement rings were originally seen as a bride price, and not as a symbol or everlasting love. A father would also give away his daughter, because the father owned his daughter and now the husband would own his wife. This is why a woman had to pledge to "love, honour and obey."
Infidelity also only counted for women. In a biblical sense, only a woman could be an adulterer, and the commandment applied only to women. Men were allowed to have as many wives as they wished. Some religions still believe this. Polygamy is still very popular through-out much of the world. Its just not as popular in western society. The ring was seen a sign of his property, and some rings even featured his family crest, since she would be leaving her own family and joining his family. The Chinese still refer to women as small happiness, because she will join her husband's family.
A bride price is the equivalent of the dowry that the bride's family pays the groom. A dowry came in the form of money, goods or estate. Only some cultures allowed women to own property, such as viking culture, whereas most other cultures had to hand-down property through their husbands. So, if a woman wanted to retain ownership of that estate, then she would have to give it to her husband, so that she could remain in the estate and eventually either pass it down to her sons or her son-in-law.
Irish had a Claddagh ring, which was similar to the modern engagement, promise or friendship ring. It was worn on the right hand while single, and then was transferred to the left hand to indicated she was engaged. Also, this was commonly given to her by a figure other than her lover. Mother's usually passed it down to their daughters, or grandmothers would pass it down to their granddaughters Many young Irish women wore the Claddagh ring, on their right hand, with the crown facing their finger-tips as a sign they were single and were looking for love. Once in a relationship the woman would then point the crown towards her wrist. Once engaged, she would then point the crown towards her finger-tips on her left hand, and once married would point the crown towards her wrist on he left hand.
The modern engagement ring, until very recently was not purchased, but inherited. The groom would acquire either his mother's or his grandmother's engagement ring, and that ring would become his wife's ring. This ring would continue to be passed-on through many generations. Similarly, the brides dress would be handed down to her from her mother or grandmother, and would be shared with many generations.
The idea that people would even want to buy modern rings or modern dresses, was unheard of, especially because of how expensive they were, and how poor most newly-wed couples were. In some cases, if there were multiple daughters, it would go either to the eldest, or the first to marry.
The groom simply did not wear one, because of how costly they were, and because the brides mother was not going to give her daughter a ring to present to her groom, especially if she had sons, who the ring would be passed down to.
Not all marriages, even to this day occur for love. Arranged marriages are still very popular, even in countries, like India, where they are now technically illegal. The nation doesn't really enforce the law, and many people still agree to arranged marriages. The idea that a husband would wear a ring, suggests more affection, and this is not really the case, in all marriages, even modern-day marriages.
One reason its considered bad luck to see the bride on her wedding day, is because some grooms would leave, if they saw the bride. A bride also wore a veil, until she was officially wed, to conceal her face. A groom didn't always know which woman he would wed, especially if there were multiple available sisters in a family.
Some cultures use wedding dresses and rings for other customs too, such as baptism or another right of womanly passage. The ring is seen as feminine.
men are starting to wear them as women buy them a ring at same time. Many men now have a ring that is added onto or worn on the other finger, or a necklet is bought.
engagement rings aren't necessary, they were and are a token bond of promise. If the man breaks the promise she keeps the ring, the asset, that is why they are not supposed to be cheap.
If she breaks it, then he gets it back, if they both break it off, they make a joint decision.