[Steel Wolf]

You're also arguing that marriages in which both partners expressly never desire to have children should be forbidden by the state.

No. I know plenty of people that expressly stated a desire to never have kids.

They had kids.

Thus, marriage exists for the benefit of children, even from people who change their minds.

[The Green Goblin]

You're arguing that if I've had a vasectomy and my fiancee has had a hysterectomy and neither of us want to ever adopt kids and are medically unable to have them, then we shouldn't be allowed by the state to be married.

[The Green Goblin]

You're also arguing that people who are too elderly to have kids or adopt them should not allowed to be married by the state.