Marriage is an outdated institution based upon unrealistic expectations. Two people are expected and pressured to stay together for their rest of their lives. Most marriages fail far long before that. Also many victims can be pressured to stay with their abusers to make their marriage work. Adulterers would get many chances to mend their marriage as their partner can find it hard to break it. There are things your partner may do that can never be forgiven, nor forgotten. With divorces so rife it's a wonder why people get hitched in the first place.
Also marriage undermines couples that decide against being married and I think that's wrong. Married partners do not deserve any tax relief privileges above anyone else. All relationships only require love and trust to work. In normal relationships homosexual people can stand toe to toe with hetrosexual couples without anyone minding or meddling. Nobody would care about multi-relationships as bigamy is a non-issue without marriages. People won't defraud the government by having bogus marriages to get asylum if marriages didn't exist. People would be more open to relationships and to ending them. People would retain more dignity. The world would be a much better place without marriage.
In the past marriages were a way of sealment with Gods blessing so it was largely a religious ceremony. Now many if not most marriages are not performed in churches. In the past marriages were also largely formed to create ties in the community and bring two different families together. Marriage used to be primary a family based institution to help rear children. Marriage also used to be defining a commitment between only a man and a woman. Now we recognise marriage as something else completely. Only a meekly contract between two consenting individuals. Nothing more. What ever marriage used to hold is lost in meaning. It's dying.
In a time where being single is what people strive to be for as long as possible, marriage still shows great dedication and morals towards love and happiness. Being single and happy is just a mere shell of fake emotions influenced by media. People who are single are always striving to be with someone they can share happiness with .