I think it depends on quite a few factors. 20-something really isn't an age where most people are fully mature, know themselves well, and know what they want for the rest of their lives. I recall being in my twenties thinking I knew it all, fell in love many times, thought this one was "the one", and having my thoughts, opinions, tastes, everything change and often.
Divorce rates are pretty high, so if you want a lifelong marriage, in my opinion you should date and live together first for at least 5 years. If you plan on marrying someone, there is no need to rush into it. You really get to know someone over time and especially when you live with them. I'm sure some disagree due to religion and upbringing, but how else will you find out if you are truly compatible, can deal with hardships, bills, illness, bad habits, disagreements, etc. I'm not saying it can't workout if you don't, but that your odds will be alot higher if you take the time to mature, get to know yourself and your partner, experience life together a bit, then get married. Marriage requires work, tolerance, love, trust, committment, laughter/fun, and desire to make it work from both partners. Too many young people & celebrities do it for the wrong reasons and too soon and then they wonder why it didn't last.
I take marriage extremely serious and don't believe in divorce. I dated my husband for nearly 2 years, then we got engaged and lived together for 6 years before marrying at age 32.
