I don’t find it hard either, but we have always been equal from childcare to chores and we both work and financially contribute, We also share the same values.
however I think many marriages are hard. Hence why so many divorces. As well as so many abusive marriages, or ones of convenience, where they both know it’s over, but they stay for the lifestyle.
So many start to resent each other, but again stay, money, division of labour , be it paid employment or housework, different social lives, and sex can be an issue, appearance changes, weight gain, personal grooming, appearance, lack of affection.
so for many I think it is hard, navigating, accepting compromise, overcoming resentment,disdain, lack of attraction.