Sophia Bush has split from her "One Tree Hill" co-star and on-screen husband Austin Nichols.
 
The couple recently ended its on/off relationship after six years of dating.
 
A source tells UsMagazine.com, "She's moving on... because she didn't think he was The One."
 
Bush was previously married to fellow co-star Chad Michael Murray in 2005, while she also romanced another castmate, actor James Lafferty.
 
Nichols broke off his engagement to artist Claire Oswalt in 2004 following a seven-year courtship.