its only hard if you make it difficult for yourselves.
marry the right person, trust, communicate, compromise.
The 'hard' comes in, in my experience with my ExH, when one tries to dominate the other, control the environment with an iron fist, or fails to support.
Marriage is give and take, and one sometimes having to carry the family, but knowing the other can and will take over when needs be. It's hard when someone just takes and takes and gives nothing back.
My Ex was an angry, domineering, shouty, selfish fucker who expected me to support him, but was NEVER there when i needed him if it interfered in what he wanted.
House had to be his way, meals when he wanted, silence if he wanted the tv on, he commanded when bed time happened, and would punish us all with threats and shouting and throwing things if he didn't get his way.
So yes, marriage is HARD, but only with the wrong person.