I don’t think it is an age thing and, while I don’t think people should marry people they don’t love, being in love is not particularly meaningful when it comes to getting married; after all throughout history and in other parts of the world people get married without knowing each-other at a younger age than we do and are (often) in more stable loving relationships than people who marry based on love in our culture.
The important thing is that you’re with someone who respects you, accepts you for who you truly are, wants similar things out of life, and you can effectively communicate with. The best way to determine this is to live with them for a year (or more) before you get engaged; and for people who don’t believe in sex before marriage (not that there are many anymore) this could just be living as a roommate.
The most common thing that leads to divorce is people fighting over money, which is entirely related to budgeting, and as a single person it is easy to budget because you will (obviously) have found all the decisions you made acceptable. If you’re with a person who always makes you make unacceptable budgetary sacrifices while they live an (in your mind) excessive lifestyle it will be difficult to remain married; and (as is commonly the case) if you both feel that way and are fighting over it the marriage won’t last.
