Lily Collins claims honesty is the key to having a good relationship.

The 25-year-old actress doesn't think there's an ultimate secret to falling in love and staying in love but believes being truthful with your partner builds the best foundation for long-term happiness.

Speaking to BANG Showbiz, she said: ''It doesn't matter how long it takes to get there, to be in love, as long as in the end people are honest. When you're honest it pays off.

''Everyone has their own speed at which they're honest, so I would say it's beautiful but it depends on person to person.''

Lily plays Rosie Dunne, the romantic interest of Sam Clafin's alter ego Alex Stewart in her latest role in 'Love, Rosie', which sees the two best friends slowly realize they have fallen for each other.

The romantic comedy is full of awkward moments and the starlet - whose parents are musician Phil Collins and his second wife Jill Tavelman - says many of the embarrassing scenes are very true to life.

Lily explained: ''Everyone has a friend who has gone through something as funny as some of the moments in there.

''We kind of shine more light on those awkward moments and say it's OK everyone goes through those moments.''

'Love, Rosie' also stars Tamsin Egerton, Suki Waterhouse, Jaime Winstone and Art Parkinson.