We've moved on a bit from the days of the Hay's code, when you could only show a couple in bed together if they each had a leg on the floor on opposite sides of the bed.
But whilst there is plenty of bonking on the silver screen today, romantic films are generally a bit different as all the serious action is supposed to happen after the credits have rolled.
Or does it.
Here are five romantic movies where the end credits might not have been followed by some action between the sheets.
1. Elaine and Benjamin in The Graduate (1967)
Having escaped the clutches of Mrs Robinson and persuaded Katharine Ross not to marry the boring Carl, the film ends with Dustin Hoffman looking a little uncertain about what he has actually done.
I expect most romantic movies would probably end this way if the cameras kept rolling for a few extra minutes. Or it could just be that be that Benjamin is a little disappointed to be riding on a Greyhound bus after spending the rest of the film in a drop dead gorgeous Alfa Romeo convertible.
2. Walter and Hildy in His Girl Friday (1940)
Cary Grant and Rosalind Russell play a divorced couple in the news business. You suspect she wore the trousers, which was probably fine as Cary Grant preferred ladies' dresses. Certainly Grant's character seemed to think so and he spends the film trying to woo her back using a variety of means, including getting her new finance arrested over and over again.
The film is just an excuse for the two leads, both at the top of their game, to trade witty banter. In the end however they both end up preferring work to marriage and got their separate ways.
Just as well really as together they stole every scene they were in.
3. Osgood Fielding III and "Daphne" in Some Like It Hot (1959)
We know that Marilyn Monroe and Tony Curtis didn't work out as couple, but maybe Osgood and "Daphne" do. He certainly seems happy.
Nobody's perfect, but this film is.
4. Laura and Alec in Brief Encounter (1945)
Supposedly this is because they are both married, but as it was adapted from a Noel Coward play the actual reason may be slightly different.
A metaphor for same sex romance in a less progressive age it may be, but is still one of the most tear jerkingly romantic films ever made which has made an obscure railway station in Lancashire a popular tourist destination.
5. Rick and Ilsa in Casablanca (1942)
We presume this was a supreme act of selflessness although people have subsequently read rather a lot into Boggy saying to Claude Rains' Police Captain "This could be the beginning of a beautiful friendship."