Jemy, one question leaps to mind, but please don't feel you have to answer it. What is YOUR relationship position? Are you in one, have you had a bad experience? I'm not prying, it's just that most of us involved in this excellent discussion are married or in a solid relationship and that might make a difference to ours, vs your perceptions!!
Im 29 now. I have lived with my girlfriend for five years and we plan to get married once both lost some weight. The plan is to visit Japan and marry on the Swedish ambassady, maybe later arranging some kind of dinner with friends/family.
My point of view is mostly an effect of my culture.
The marriage rate rate in Sweden is really low.
Like many swedes I consider marriage to be a huge step in life, one not taken lightly. It's culturally unliked to getting married at a young age and at least you are supposed to finish school (~22-25) and get a job before you get married. People who marry sooner than that are not taken too seriously.
Most live together for many years before they marry (at least 3-5 years). 30 years of age represent the point in life in which you should be married no matter what.
Marriage is also associated with a costly ceremony which young people in Sweden cannot afford, perhaps an effect of a messed up labor market meaning that it's very difficult for young people to get a job especially if they do not have higher education.
Some do not wish to live together at all and they do not marry either. Single mothers or people who live apart is not uncommon.
Sweden have had legal unions between homosexuals for many years which offers the same advantages as marriage. Marriage between homosexuals is "just a matter of time" and if there was a vote today it would probably pass. The largest church (representing the majority of all christians) is actually in favor of homosexual weddings but allow priests to opt out if they do not wish to do it.
Removing marriage from swedish law entirely was also in discussion a few years ago, the idea was to replace it with some kind of universal recognition for people living together. The party standing behind it was dissolved though and maybe it was not taken too seriously. We already have laws that support people who live together, which includes support for dividing the household if breaking up. At least one of the smaller parties are also positive to polygami.