I disagree with that. However, living together first can devalue the meaning of being married when it's that value that often will get them through the hard times.
What do you need to know about your future life mate? I'd say at least the following:
- Do you actually like each other?
- Do you share the same values?
- Are your religious beliefs compatible?
- Do you both want kids? And how many?
- Will you share the same child-rearing philosophy?
- Do you have the same views about daycare and/or full-time moms?
- Are you good/bad money managers?
- Where do you want to homestead?
- How important are your diets, exercise, and physical fitness?
- Are your careers compatible?
- Do you get along with in-laws and how important a role will they play?
There's more, but you can learn about all of this without living together.