Dominic Cooper thinks actors date their co-stars because of ''dynamic chemistry''.

The 34-year-old actor - who previously dated fellow 'Mamma Mia!' star Amanda Seyfried and has been romantically linked to actresses Ruth Negga and Gemma Arterton - believes on-set romances are understandable because of the effects of portraying a love affair on screen, coupled with spending a lot of time together.

He said: ''There are parts where for 12 hours on that day you are portraying someone who is so in love that they are on the cusp of insanity- so you can understand that dynamic chemistry.''

Dominic - who Amanda later accused of continuing to romance his former girlfriend while they were dating - admitted he hates being the subject of public scrutiny because speculation about his personal life can be ''really damaging''.

He said: ''Fame is a difficult thing to be thrown into and I've been burned in the past.

''The rumour mill can be funny, but unfortunately it can also be really damaging''.

The British actor also insisted his increased fame hasn't changed his relationship with his friends and family - though they sometimes mock him.

He told Seven magazine: ''I hope not. They're the people I'm happiest with. The majority are friends from a long time ago.

And although I know that they're incredibly proud of me, I generally just get an incredible amount of abuse from them.''