IMO, singles have to look out for being pushed into rushing into an engagement after only a few short weeks of dating someone. They also have to forget everything they were brainwashed to believe in Seminary, lose the stars in their eyes about shidduchim and their future as Mrs. Kollel Wife, and cash a reality check, before making such an important decision. They need to focus on the middos that THEY observe in the boy or girl, how that person treats tradespeople, waiters, their parents and siblings. They need to determine if the person has outlandish opinions or demands that need to be met.
How do the parents treat each OTHER (especially the father treating his wife with respect). They need to know what a budget looks like, and discuss how they will live financially should Mommy and Totty NOT be able to help with support. What happens when they have kids (as they probably will, right away)? Too many couples do not discuss these things fully. They focus on the transient outer trappings of being engaged, the excitement, the vort, the wedding plans, but not on the things that matter because they are supposed to last a lifetime.
One boy I met together with his kallah for the first time, expressed the definite demand to have an extremely small (and I mean exactly that) wedding, and no need for people to be dancing and making it lebedig. Even when his kallah questioned that idea, he told her he dislikes groups of people, and that is that. Then when he paused and she began to make a comment, he yelled at her in front of us, that he was not finished speaking. When he saw the look on our faces at his rudeness, he softened his tone, but in my mind the damage was done. She called us the next day to ask our opinion, and I told her that while I tried never to make judgments to someone, especially a kallah, I felt very uneasy about this guy, and felt she deserved better treatment and derech eretz from someone who supposedly loved her. She ended up breaking it off (her parents were ecstatic and thanked me a million times – (ooh, maybe I should have received NON-shadchanus gelt for saving her from a bad marriage… JUST KIDDING), and she married a truly fine, ehrlich mensch later that year.
My children have at least four friends among them, who married and divorced within a year or two at most. That appalls me.