1. What are my bad habits?
If you want to spend the rest of your life with someone, you should first work out whether or not they're going to last that long in your company without going insane.
2. Do you think you could handle joint finances?
Marriage doesn't just involve a fancy ceremony and ticking a different box on official forms, it also means making joint investments, splashing out on holidays together, and trusting one another with money. So if your partner has some kind of debt problem, or is notoriously terrible at handling their finances, you might want to hold off for a while.
3. What are your religious beliefs?
This is something you definitely should know before getting too far into the dating phase, but it's super important to talk through before marriage. Would they expect you to join their religion? Do you expect them to join yours? Does the wedding have to include/exclude certain practices?
4. How do you imagine your wedding to be?
Come on guys, this is a fairly basic one. If you strongly differ on this, the chances are you'll encounter many other conflicts down the line.
5. Cats or dogs?
Or neither? You need to know before one of you comes home with a labrador and the other says they're more of a cat person.
6. Do you think marriage would change our relationship?
And if it would, how? Everyone has different ideas about what a marriage should be like, so you don't want to get legally bonded to someone only for them to turn around and say that you now have to do all the housework or childcare or whatever else it may be.
7. What are your life goals?
There's no point marrying someone if, five years down the line, they announce they want to sell everything you own and travel the world - especially if you had every intention of just settling down and raising a family. Some people just aren't compatible, and it sucks, but it's better to know that before you get wed.
8. What would your dream home be like?
Do they want a life of luxury or a humble home? Are they a city dweller or a countryside kinda person? Will their house look "well-loved" or brand new and pristine? You should really know all this, seeing as you're going to be sharing in it.
9. What sort of career do you see yourself having?
If you're super career driven, but your partner is the type of person who'll just take whatever opportunity comes their way, then you may have a problem on your hands. Having different levels of ambition will ultimately lead to tension, and maybe become a dealbreaker. What's more, if their career requires them to travel, or stay in a certain place, and yours requires the opposite, then that's a huge dilemma.
10. How would you deal with a divorce?
It sucks to have to ask this, but you need to have a contingency plan when you enter something as serious as a marriage. If neither of you can sensibly plan for a worst-case scenario, maybe you aren't in the right place to plan for the best.