Because that's how it works.
It's not people having affection for each other and working on their differences in order to be together.
It's a magical match. Once you've found your soulmate everyhing about them will be perfect for you forever, taking no effort.
You... you did find your soulmates did you anons? You didn't stay together with someone that has to put effort into pleasing you? That would be doomed to fail.