What makes a good marriage?

This is a very sticky question.
In my opinion, it would depend very much upon the people in this equation.

Some people see marriage as the culmination of a beautiful courtship - but to me, that's an incorrect view, because what hits the peak comes right down on the other side.

Some people see it as a necessity because it's what people do when they hit a certain age - which is also dangerous, because these same people have a higher tendency to grab whoever's nearby and get that paper signed and sealed.

Some people see it as a means to avoid what they will otherwise experience, lonely mid-life/old age. Which again doesn't fix things, because you could well be separated before you hit the projected mid-life crises.

Some people think they need to have children, pro-create to ensure a lineage for their family. But children do not always keep the marriage together - it's stressful and joyful on one slice and not everyone can cut it.

Some people think, its better to get married because then sex becomes safer, without thinking that with marriage, sex is never just sex anymore, simply because the dynamics of the relationship has changed, and with it, everything else on a subconscious level.

Some people marry because they love a person, but just as love has the ability to develop and grow, it has an equal ability to fade and die. After that happens, it's just responsibility to the vows that would keep the marriage together.

So, what makes a good marriage?
It's not about any of these things.

It's about whether we have enough patience to nurture the relationship further. Its' about whether we found another person who has the same ideals about building the relationship.
There must be 2 willing parties with similar targets otherwise, it becomes stressful for the other person and children as add-ons, do not make it any easier.
What we do not want is for the marriage to become a responsibility more than a relationship.
To do that, we should marry for the right reasons, which is for ourselves, not us alone, but ourselves as in for both parties - It should never be for someone else, something else or worse still, because it's time.

Marriage brings with it happiness, sadness, security, expectations, disappointments and stress - in random order - but what makes it work is our own preferred order of things and how we make sense of it.
It's not a bad thing, it's just a bad thing for me.