I'm 9 months to my golden anniversary. We've had our ups and downs, separated for half a year, about 15 years ago, but overcame our differences.
My younger sister has been married for 55 years.
My older sister, twice widowed, is on her third husband.
My younger brother has been with his fourth wife some 25 years. (I think he kissed a lot of frogs to find his princess!)
Everyone is different - there's no "one size fits all" formula.

Divorced once after 4 years of marriage and another 6 dating. She didn't want to put any effort into our marriage anymore and we faded. I don't think we were perfect, but I think there's a significant difference in people who work through the tough times and people who won't.

Marriage is a proposition that TWO people can behave like responsible grownups, be kind to one another, forgive failures, and be friends for a lifetime. Companionship and intimacy along with a financial partnership that makes two together stronger than two apart are some strong motivators to get it right. Making it work requires both to do their best. You can't demand that someone else change for you, but if they want change from you that makes sense, you have to be willing to try to change for them. You have to be firm about the deal-breakers. No one should try to be a martyr and I promise no one wants to be married to one. It's a delicate balance and it's not a wonder that some people never get it right. For me, the upside is worth it, but only because I know my husband also values being day to day happy over being right. Taking care of yourself plus one other person, and setting a high bar for both: that works for me.

Divorced, once. I was married for about 2 years.

I don't know many couples who have been married a long time and still appear happy. One is also statistically unusual for another reason -- they married after dating a week. They saw each other and just knew.
I'm adding because I apparently wasn't paying good attention to the question. I've been married twice for a grand total of six years. I've been single most of my adult life. I feel like I understand men about as well as I do armadillos. For example, on his way out, my first husband snarled at me that I didn't want a husband, I wanted a best friend to have sex with. ???????? I still don't get why that's a problem.The second marriage was a mistake for too many reasons to recount. I've been single since. Just haven't met anyone with whom the effort would be worth it. I am set in my ways and have a nice life. I am choosing to observe the stop sign.

Married once, divorced once. That was plenty for me. Somebody said... "smart people learn from others mistakes". She is working toward her third marriage. I wish her the best. But I already told her... you ain't going to find me. I was as I am... "That Unique Pain In The Ass" but after 18 years of divorce we dance better salsa together now than when married for 19 years.

I was married once for a year and divorced when he wanted me to drop my pursuit of medical school. I was far into that when I met him. My parents have been married 64 years. THey love each other and have put up with a lot of stuff between themselves mostly related to personality

I'm happily married, only marriage I've had. My parents have been married 38 years and they are cute. My grandparents were married 61 years, my grandfather passed away at 91 years old.

My husband's partners are divorced. Mother had 2 marriages and 2 divorces. His father remarried and has been with his step mom for 20 years.

Only once and that was enough for me, also no more kids. It was due to what I learned about myself and not the fault of who I was married to or to women in general.