Distance seems to be the culprit.
She of "Oz the Great and Powerful" lives in Brooklyn with her 7-year-old daughter Matilda, whom Williams had with the late Heath Ledger. She hit the film's Los Angeles premiere earlier this month without Segel in tow.
Segel, who is one of the stars of the CBS series "How I Met Your Mother," primarily resides in Los Angeles, where the comedy films.
The couple began dating in March 2012 and kept a relatively low profile throughout their relationship. They are said to have been introduced by Williams' good friend and "Dawson's Creek" costar Busy Philipps, who was also on "Freaks and Geeks" with Segel. Williams and Segel reportedly moved in to a Brooklyn apartment together last year.