It gives you a chance to discuss a number of critical questions that an appalling % of couples never discuss until it blows their marriage up. E.g.: -How do you communicate issues and resolve conflicts? -Do you want kids and when? -Who's going to take care of them? -What lifestyle do you expect and how will you pay for it? -What virtues make you want to marry your fiancee? -What boring, practical things do each of you bring to the relationship (e.g. resources, skills, etc) -How will you handle conflict with relatives? -Do you have religious differences? -Who wins if you have a mutually exclusive conflict, does that vary by domain, and why? -Whose job takes priority? -Where do you want to live? -What are your partner's flaws or subjectively annoying habits, and have you mitigated or accepted them? -How do you handle differences in financial goals? -What are your stances on divorce? -Do you love people or things more? -Who wins in a dispute between your spouse and Muy Mainstream Propaganda -In what ways do you expect your spouse to change, and are those ways probable? The list goes on, but you get the idea. Churches push premarital counseling to get you to both discuss these types of questions in front of a neutral third party who can ensure you both reach a consensus and that it's not a delusional bullshit consensus like "it'll work out". Because it wont. E.g. my spouse has a lifelong flaw of throwing laundry on the floor throughout the house rather than the hamper. I do most of the laundry. This could be a source of conflict had we not talked about it and solved it through the simple expedient of putting the laundry room on the opposite end of the house from the hamper. Since I have to walk through the entire house to reach the washer anyway, snagging stray articles of clothing as I go is now negligible effort rather than a point of conflict. Couples who hadn't talked about it? Oooh boy could that have been a problem, particularly if you did laundry weekly rather than daily.