IMO, there is so much to discover, even non sexual, about a life long partner that can't be discovered in a chaperone type environment enforced by the JW culture. So a marriage is like signing a contract without reading the fine print.
Realistically, there are discoveries that are not learned until after marriage even for non JWs who, having the opportunity, weren't honest and open during the dating period resulting in unhappy marriages and divorce.
(caveat emptor)