Probably not, the best part of 사랑 is coming to realization that 당신 want to be with this person forever, and that 당신 want to end up with them.
But if 당신 know, i'd think it'd kill a lot of the relationship, i mean you'd know you'd end up together, so why bother with all the wooing and courting.
Yes.I would then at least know I won't be lonely my whole life. It's just not good enough having someone tell me that there's someone out there for me.