Answer by an Anonymous User on Quora,
I worked with celebrities as an assistant for about five years, been in the industry longer than that due to my father's job. I've never seen or heard of a celebrity date or break up with another celebrity for publicity. I don't know if it happens among B/C-list celebrities like the Kardashians, but among A-listers, it never happens, it's just a myth.
Other than the regular divorce reasons like growing apart, this is why:
Not just celebrities, for all rich people a divorce is easier to decide than most non-rich people. For me, if I wanted to get a divorce, I'd think about the financial side like lawyer expenses, living on one income after getting a divorce, and worry that if I'll ever meet someone I can love again. All these would make me work harder and longer on the problems I have in my marriage. To a person who is not rich, a marriage is one of the few big supports in life. Rich people have a lot of supports -- from ability to shop and travel to start a business, they have so many things in their lives to keep them occupied, get passionate about, and cheer up.
And celebrities always have people throwing themselves at them. Not just because they are rich, I'm not talking about gold-diggers, but being rich makes them able to socialize a lot more with other rich, famous people (read: eligible bachelors and bachelorettes.), they can also often travel and meet people. A rich person will have more belief in meeting someone they can love again, than someone who lives in a small neighborhood and only gets to meet a limited number of people. Which makes the decision to get a divorce easier.
Things get real when you're married.
Celebrities are like the popular kids in school. We all know them at some level and have an idea on what kind of people they are based on their interviews, news about them, etc. So even celebrities can and do develop crushes on each other over their image in the media. When you're in a relationship with one of them, you get to see the real them. From a movie/music star, they go to being someone's son, the guy who has a crazy uncle, the guy who gets scared of spiders, the guy who is not romantic at all or too mushy, the guy who smells bad in the morning. Some people get disappointed when they see those things because when they met the celebrity, they had expectations over their image, and expectations usually bring disappointment. And some people tolerate the things they dislike about real them for a while, they think they like the things they actually dislike, and those become unavoidable when you're married.
Actors, models, singers, directors, even some writers travel a lot. They spend months away from home at times. If a woman is celebrity and her husband isn't, it's easier to manage the schedule, the man can travel with his wife. Though even then, the man might find it too tiring after a while and want to settle down somewhere instead of going from one place to another all the time, or when they have a child, one of them will have to stay with the kids so they can go to school. This might cause a lot of problems like the lack of sex, not getting emotional support in person, and not feeling like you're married when you actually are. And when two celebrities are married, they both have a busy schedule. When one of them is giving a concert in Paris, the other one has to give a concert or promote a movie in New York. (When you look at the most long-lasting celebrity marriages, one is a celebrity and his/her spouse isn't.)
Temptation is higher when you're a celebrity
A guy/woman who works at a company will not have anyone kiss them as a part of their job. Actors get to kiss people in movies, singers get to dance with dancers on the stage. Such physical contacts can increase little crushes or create a crush. If that actor is married but have some troubles in his marriage, or doesn't have any problems, but the relationship lost its first passionate excitement like it happens to every long relationship, kissing someone might make him push away from his wife more and might cause him want to go after new excitements, especially sexual ones. Not to mention, celebrities have a lot of people hitting on them all the time.
Divorce rate is very high in the USA, including in Hollywood. Even in UK (where divorce rate is also not low at all) there are less divorces. For an American celebrity, getting a divorce is "one of the things many people (celebrities) do here," for a British celebrity, getting a divorce would more feel like a fail and unusual because they see Hugh Laurie and his wife Jo Green, Victoria and David Beckham, Sting and Trudie Styler, Colin Firth and Livia Giuggioli, Ewan McGregor and Eve Mavrakis, David Bowie and Iman, Daniel Day-Lewis and Rebecca Miller, Ricky Gervais and Jane Fallon, Christian Bale and Sandra Blažić ... and on and on
Statistically, couples who have a little or zero age gap between each other have better and longer marriages. Among celebrity couples in Hollywood, the age gap gets bigger and bigger by year. Everyone might get attracted to youth, but actually dating with someone who is significantly older/younger than you is seen as something bizarre in a lot of countries outside the US. Again, it's easier for celebrities to find a partner. If you're a 35 year old businessman, chances are you won't find many 25 year olds who will want to date you. A 35 year old actor will have 25 year old women who like him because he's famous, rich and doesn't seem like a pervert in the media. And when a 35 year old guy dates a 25 year old woman, that relationship has a lower chance to work out than a 35&33 year old couple.
When millions of people tell you that you are awesome, scream when they see you, it's easy to believe you are indeed awesome and treat your spouse like you are better than them and know everything better than them. It doesn't happen to all celebrities, or even most for that matter, but especially among newly-celebs, it's not something too unusual to come across.