Americans have been waiting until later in life to get married for some time now — but the idea of couples marrying after they have children has become a thing, of sorts, in Hollywood in recent years.

A long list of celebrities either waited until after children were born or never married at all: Bridget Moynahan and Tom Brady; Mary Louise Parker and Billy Crudup; Susan Sarandon and Tim Robbins; Kourtney Kardashian and Scott Disick; Brad Pitt and Angelina Jolie; Adele and Simon Konecki; and Goldie Hawn and Kurt Russell, to name but a few.

Bradley Cooper, famous Hollywood bachelor and notorious dater of fashion models, now can add his name to this list. Cooper’s girlfriend, Victoria’s Secret model Irina Shayk, reportedly is pregnant with the couple’s first child. They’ve been dating since the spring of 2015. Cooper had said he hoped to be a father one day.

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“I really hope I have that experience in my life,” he told Details magazine back in 2013. “I saw how much joy fatherhood gave my own dad. You go through stages in your life, and fatherhood seems like a natural stage.”

He does regret not having had children while his father was alive — and wishes his children would have met their grandfather.

There was a time when unplanned pregnancy often meant that a shotgun wedding was arranged to avoid embarrassment to the family and the couple, but the concept of love leading to marriage and then to children seems to have become bizarrely passe.

For years, Brad Pitt and Angelina Jolie worked together — publicly and famously — to build a baseball team of natural and adopted children before tying the knot; their recent messy divorce is still of fascination to many people. Angelina looked at her children as a lifetime commitment, but marriage always seemed a questionable proposition.

Related: The Four Big Problems in Every Marriage

Mila Kunis and Ashton Kutcher got engaged in February 2014, gave birth to their first child that October — then married in July 2015.

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Actress Amanda Seyfried of “Les Miserables” and “Ted 2” fame last month announced she and her fiancé, Thomas Sadowski, were expecting their first child.

Earlier this year, French actress Marion Cotillard announced on Instagram her second pregnancy with longtime partner Guillaume Canet. They’ve been together since 2007 and already have a son, but they still have not announced any plans to marry.

Ballerina Melanie Hamrick will be having her first child with 72-year-old boyfriend and Rolling Stones legend Mick Jagger. This will be the rocker’s eighth child.

Our relationships, sadly, seem to grow more cynical about commitment.

Singer Alicia Keys confirmed getting engaged in May 2010, married in July — then gave birth to a son in October the same year.

Actress Scarlett Johansson gave birth in 2014 to her first child, then married her longtime fiancé, Romain Dauriac, a month later.

Reality star Kim Kardashian and Kanye West welcomed their first child in June 2013, then got married in May 2014.

One Direction star Liam Payne announced last week that his girlfriend is expecting a baby.

Many of these couples eventually married, but many more either waited until after their children were born or even still not have married.

This reflects a national trend to some extent. The average age of marriage is at an all-time high — 28 years old — in the U.S. According to the Centers for Disease Control and Prevention, the average age of Americans having their first sexual experience is 17. Now, 55 percent of births are outside marriage, according to the research group Child Trends. That means a lot of people are having a lot of sex — and children — before marriage.

Related: Can Brad and Angie Pivot to the Kids?

Our relationships, sadly, seem to grow more cynical about commitment. Children of the 1980s and ’90s became wary of tying the knot after seeing divorces in their own families and communities.

Feminism has encouraged women to resist being legally and eternally attached to the fathers of their children. At the same time, men now feel less societal pressure to take responsibility for the children they father.

Even among those who do step up, it seems easier to endure babies crying at 4 a.m. than to make a one-hour trip to the courthouse. Is marriage meaningless to these people? What does it mean for their children? And Hollywood fans?

Children are a long-term commitment. It’s a problem when the parents themselves don’t know where their relationship will be in the long term. As a society, we do all this backwards. We forget the importance of drawing legal and social lines in our lives and of assuring our children that their lives will have some consistency.

It’s too much to expect Hollywood to encourage virtue and commitment among parents — but must the stars always set the opposite example?