Picking the right partner is EVERYTHING when it comes to a successful marriage
You and your spouse don't have to be compatible on EVERYTHING as long as you are in mental/spiritual/physical love and in agreement on the major issues. Gender roles, sex/romance, religion, finances, rearing children, each other's families and you guys can hold an interesting conversation with one another. Adaptability>compatibility.
Also, brush up on your negotiation skills because arguments inevitably come in a marriage and you and your SO will need to be able to meet in the middle for an ameliorable agreement to keep the foundation of love & trust strong.
You don't need to get married if you're worried about a prenup because you shouldn't go into a marriage thinking about divorce, marriage is supposed to last forever.