Hmmmmm, for me, unpredictability. I hate structure, loath it in fact. A poem explains my lifestyle, it's called dust if you must.

Dust if you must but wouldn't it be better
To paint a picture or write a letter.
Bake a cake or plant a seed;
Ponder the difference between want and need?

Dust if you must but theres not much time,
With rivers to swim and mountains to climb;
Music to hear, books to read;
Friends to cherish and life to lead.

Dust if you must but the world's out there
With the sun in your eyes and the wind in your hair;
A flutter of snow, a shower of rain,
This day will not come around again.

Dust if you must, but bear in mind,
Old age will come and it's not kind.
And when you go (and go you must)
You, yourself, will make more dust.

Life's to short to script your day, eat your tea in the same place at the same time, nothing grinds me down more.

Trust, friendship or just do as your told.

Trust, friendship or just do as your told.

Usually, I guess, but not for everyone (you don't need them all).........respect, loyalty, communication, trust, laughing and not being too uptight, finances, sex, and things in common like doing the same activities and liking the same music and movies etc.

depends on the couple; some thrive on chaos, others on order and predictability. Some on both - Mutual love and respect is a given, or you shouldn't be together (not withstanding the occasional moment when you want to strangle your beloved - which is just human nature).

Ultimately, despite any other factor - I think that dedication to staying together, to making life work with the other person, to devoting yourselves to the unit of the union, as well as devoting yourself to self care as well. It can be a tricky balance - and it can easily go into a dark place if both parties aren't truly dedicated to each other.

Magic.....

Common goals in what you want in a relationship. This is almost impossible to pin down because its different for every couple. Each person has things that are important to them. So one could say it comes down to relationship compatibility. This is not the same as shared interests. Someone who wants children being with someone who does not is going to always make a relationship difficult to maintain. Someone who has a high sex drive is likely not going to last long with someone who doesn't have one. People can change a bit but there are always limits.

A relationship is like a scale and everyones is different based on where they are in life, how badly they want a relationship etc. On each side is what is important to you that you can't budge much on that you have in common and on the other side is what is important to you that you don't have in common. Everyones scale has a different breaking point but once it breaks, the relationship is not a good one and will either be unhappily forced or ended.

If your scales are within tolerable levels you then must have your relationships future in common. If one values money gain as a primary goal at the expense of family and the other values family occassionally at the expense of money, its likely not going to last no matter how great it is at the begginging. Having the same or similar ending points is as important to the long term health of a relationship as compatibility.

Communication can be key to the future of the relationship as if you don't have the same future goals they are easier swayed early and entwined and compromised rather than after they have had time to settle and needs are not met.

Quite simply, what makes them last is the couple who makes them their first priority. It is important to have great communication in similar styles, matching desires where that works and complementary desries where that works.

Honesty, you can get through anything else as long as you trust each other. And communication will solve more problems than anything else I think.

Time apart.

The high cost of divorce

passion compromise and effort

Fear of being alone?

Nothing. Speaking from experience.

Here is my favorite riddle.

“How do you keep the one you love?”

No Googling/Cheating.

Time and separation...I am going out with so many people, but if they knew it, I think the relationship would stop. Nothing creepy about that....hehe

I wish I knew but from my understanding it's many things.

Compromise.

Love and work.

The cynic in me wants to say stagnation. I've know several couples who stay together because they can't imagine something different for themselves. Even though there's a preponderance of evidence pointing to the fact that one or both aren't happy. I think recognizing that the meat of the matter is in the struggle and intentionally celebrating and behaving gratefully for the moments of happiness is a good start.

Coma

The 80 yrs old couple . Been together 60 yrs.said their secret was an arrangement they made at the beginning.
She made the minor decisions
He made the major decisions.
It worked they were still in love and you know in all those years they never had a single major decision
to make.

Common courtesy. The little "every day things".

"I'm going to the kitchen. Did you want another drink?"

"I'm at the market. Need anything?"

"I was out & found your favorite juice."

" you said you needed new dress shirts a couple of weeks ago so i picked you up a few "

"Thank you for letting me use your car. I topped off the tank & vac'd it out"

I am waiting to see your thoughts @silvereyes

Respect

Communication and never going to bed angry.