AceShowbiz -

After a year of exclusively dating, "The Mortal Instruments: City of Bones" stars Lily Collins and Jamie Campbell Bower have reportedly decided to end their relationship. The romance that started on the set of their fantasy-action flick back in July 2012 would ironically be concluded on the nationwide press tour that they are currently in the thick of as they promote their forthcoming film.

Just last Friday, they were even seen holding hands at Franklin Mills Mall in Philadelphia, just days prior to their break-up. Nonetheless, they have chosen to "stay friendly" which will do them both good as they continue to make joint promotional appearances for their movie.

It's strange how a couple could part ways when just earlier this week, they were gushing about each other, like when Collins described her co-star and real-life love interest as "edgy, witting and charming." She also talked about them having this on-screen chemistry and connection that translated into something deeper outside of work, which, looking at both their dating history, is a common denominator between them, that of getting involved with their co-stars on set.

Prior to their year-long romance, Collins dated "Twilight" star Taylor Lautner whom she was cast with in the movie "Abduction". Meanwhile, Bower split up with his fiancee Bonnie Wright, who starred in the "Harry Potter" film series, whom he met while shooting "Harry Potter and the Deathly Hallows: Part I".