Richard Mylan is to replace Richard Coyle as a regular character in series 4. However, as his name has been missed from Standing Room's cast list it may be presumed he will not be regular to begin with.
Mylan will play comic bookstore owner Oliver who is introduced as Jane's blind date. Oliver is terrible at dating and a bit of a geek magnet.

Richard Coyle has decided to quit Coupling after three successful series. He was quoted to have said "People frequently come up to me and say 'Breasts' - which can take a bit of explaining to people who don’t know the show!" He will be replaced by Richard Mylan.

Standing Room are offering tickets to see series four being recorded in Teddington on each Wednesday in March. For more info go to http://www.standroom.com/shows/coupling.html

Coupling has been bought into the USA in hope that it will replace Friends as that goes into its final series. However, reports say that the actors are dull and type-cast and that it is not funny.
The original UK Coupling has been highly acclaimed in the USA though.